Top 100 Python Interview Questions You Must Prepare in 2020

In this Python Interview Questions tutorial, I will introduce you to the most frequently asked questions in Python interviews. Our Python Interview Questions is the one-stop resource from where you can boost your interview preparation. We have 100+ questions on Python Programming basics which will help you with different expertise levels to reap the maximum benefit from our blog.

Let us start by taking a look at some of the most frequently asked Python interview questions,

Q1. What is the difference between list and tuples in Python?
Q2. What are the key features of Python?
Q3. What type of language is python?
Q4. How is Python an interpreted language?
Q5. What is pep 8?
Q6. How is memory managed in Python?
Q7. What is name space in Python?
Q8. What is PYTHON PATH?
Q9. What are python modules?
Q10. What are local variables and global variables in Python?

We have compiled a list of top Python interview questions which are classified into 7 sections, namely:

• Basic Interview Questions
• OOPS Interview Questions
• Basic Python Programs
• Python Libraries Interview Questions
• Web Scraping Interview Questions
• Data Analysis Interview Questions
• Multiple Choice Questions (MCQ)

Basic Python Interview Questions

Q1. What is the difference between list and tuples in Python?

Q2. What are the key features of Python?

• Python is an interpreted language. That means that, unlike languages like C and its variants, Python does not need to be compiled before it is run. Other interpreted languages include PHP and Ruby.
• Python is dynamically typed, this means that you don’t need to state the types of variables when you declare them or anything like that. You can do things like x=111 and then x=“I’m a string” without error
• Python is well suited to object orientated programming in that it allows the definition of classes along with composition and inheritance. Python does not have access specifiers (like C++’s public, private).
• In Python, functions are first-class objects. This means that they can be assigned to variables, returned from other functions and passed into functions. Classes are also first class objects
• Writing Python code is quick but running it is often slower than compiled languages. Fortunately，Python allows the inclusion of C based extensions so bottlenecks can be optimized away and often are. The numpy package is a good example of this, it’s really quite quick because a lot of the number crunching it does isn’t actually done by Python
• Python finds use in many spheres – web applications, automation, scientific modeling, big data applications and many more. It’s also often used as “glue” code to get other languages and components to play nice.

Q3. What type of language is python? Programming or scripting?

Ans: Python is capable of scripting, but in general sense, it is considered as a general-purpose programming language. To know more about Scripting, you can refer to the Python Scripting Tutorial.

Q4.How is Python an interpreted language?

Ans: An interpreted language is any programming language which is not in machine level code before runtime. Therefore, Python is an interpreted language.

Q5.What is pep 8?

Ans: PEP stands for Python Enhancement Proposal. It is a set of rules that specify how to format Python code for maximum readability.

Q6. How is memory managed in Python?

Ans:

• Memory management in python is managed by Python private heap space. All Python objects and data structures are located in a private heap. The programmer does not have access to this private heap. The python interpreter takes care of this instead.
• The allocation of heap space for Python objects is done by Python’s memory manager. The core API gives access to some tools for the programmer to code.
• Python also has an inbuilt garbage collector, which recycles all the unused memory and so that it can be made available to the heap space.

Q7. What is namespace in Python?

Ans: A namespace is a naming system used to make sure that names are unique to avoid naming conflicts.

Q8. What is PYTHONPATH?

Ans: It is an environment variable which is used when a module is imported. Whenever a module is imported, PYTHONPATH is also looked up to check for the presence of the imported modules in various directories. The interpreter uses it to determine which module to load.

Q9. What are python modules? Name some commonly used built-in modules in Python?

Ans: Python modules are files containing Python code. This code can either be functions classes or variables. A Python module is a .py file containing executable code.

Some of the commonly used built-in modules are:

• os
• sys
• math
• random
• data time
• JSON

Q10.What are local variables and global variables in Python?

Global Variables:

Variables declared outside a function or in global space are called global variables. These variables can be accessed by any function in the program.

Local Variables:

Any variable declared inside a function is known as a local variable. This variable is present in the local space and not in the global space.

Example:

a=2
def add():
b=3
c=a+b
print(c)
add()

Output: 5

When you try to access the local variable outside the function add(), it will throw an error.

Q11. Is python case sensitive?

Ans: Yes. Python is a case sensitive language.

Q12.What is type conversion in Python?

Ans: Type conversion refers to the conversion of one data type iinto another.

int() – converts any data type into integer type
float() – converts any data type into float type
ord() – converts characters into integer
hex() – converts integers to hexadecimal
oct() – converts integer to octal
tuple() – This function is used to convert to a tuple.
set() – This function returns the type after converting to set.
list() – This function is used to convert any data type to a list type.
dict() – This function is used to convert a tuple of order (key,value) into a dictionary.
str() – Used to convert integer into a string.
complex(real,imag) – This functionconverts real numbers to complex(real,imag) number.

Q13. How to install Python on Windows and set path variable?

Ans: To install Python on Windows, follow the below steps:

• Install python from this link: https://www.python.org/downloads/
• After this, install it on your PC. Look for the location where PYTHON has been installed on your PC using the following command on your command prompt: cmd python.
• Then go to advanced system settings and add a new variable and name it as PYTHON_NAME and paste the copied path.
• Look for the path variable, select its value and select ‘edit’.
• Add a semicolon towards the end of the value if it’s not present and then type %PYTHON_HOME%

Q14. Is indentation required in python?

Ans: Indentation is necessary for Python. It specifies a block of code. All code within loops, classes, functions, etc is specified within an indented block. It is usually done using four space characters. If your code is not indented necessarily, it will not execute accurately and will throw errors as well.

Q15. What is the difference between Python Arrays and lists?

Ans: Arrays and lists, in Python, have the same way of storing data. But, arrays can hold only a single data type elements whereas lists can hold any data type elements.

Example:

import array as arr
My_Array=arr.array('i',[1,2,3,4])
My_list=[1,'abc',1.20]
print(My_Array)
print(My_list)

Output:
array(‘i’, [1, 2, 3, 4]) [1, ‘abc’, 1.2]

Q16. What are functions in Python?

Ans: A function is a block of code which is executed only when it is called. To define a Python function, the def keyword is used.

Example:

def Newfunc():
print("Hi, Welcome to Morioh")
Newfunc(); #calling the function

Output: Hi, Welcome to Morioh

Q17.What is init?

Ans: init is a method or constructor in Python. This method is automatically called to allocate memory when a new object/ instance of a class is created. All classes have the init method.

Here is an example of how to use it.

class Employee:
def __init__(self, name, age,salary):
self.name = name
self.age = age
self.salary = 20000
E1 = Employee("XYZ", 23, 20000)
# E1 is the instance of class Employee.
#__init__ allocates memory for E1. 
print(E1.name)
print(E1.age)
print(E1.salary)

Output:
XYZ
23
20000

Q18.What is a lambda function?

Ans: An anonymous function is known as a lambda function. This function can have any number of parameters but, can have just one statement.

Example:

a = lambda x,y : x+y
print(a(5, 6))

Output: 11

Q19. What is self in Python?

Ans: Self is an instance or an object of a class. In Python, this is explicitly included as the first parameter. However, this is not the case in Java where it’s optional. It helps to differentiate between the methods and attributes of a class with local variables.

The self variable in the init method refers to the newly created object while in other methods, it refers to the object whose method was called.

Q20. How does break, continue and pass work?

Q21. What does (::-1} do?

Ans: [::-1] is used to reverse the order of an array or a sequence.
For example:

import array as arr
My_Array=arr.array('i',[1,2,3,4,5])
My_Array[::-1]

Output: array(‘i’, [5, 4, 3, 2, 1])
[::-1] reprints a reversed copy of ordered data structures such as an array or a list. the original array or list remains unchanged.

Q22. How can you randomize the items of a list in place in Python?

Ans: Consider the example shown below:

from random import shuffle
x = ['Keep', 'The', 'Blue', 'Flag', 'Flying', 'High']
shuffle(x)
print(x)

The output of the following code is as below.

[‘Flying’, ‘Keep’, ‘Blue’, ‘High’, ‘The’, ‘Flag’]

Q23. What are python iterators?

Ans: Iterators are objects which can be traversed though or iterated upon.

Q24. How can you generate random numbers in Python?

Ans: Random module is the standard module that is used to generate a random number. The method is defined as:

import random
random.random

The statement random.random() method return the floating point number that is in the range of (0, 1). The function generates random float numbers. The methods that are used with the random class are the bound methods of the hidden instances. The instances of the Random can be done to show the multi-threading programs that creates a different instance of individual threads. The other random generators that are used in this are:

• randrange(a, b): it chooses an integer and define the range in-between (a, b). It returns the elements by selecting it randomly from the range that is specified. It doesn’t build a range object.
• uniform(a, b): it chooses a floating point number that is defined in the range of (a,b).Iyt returns the floating point number
• normalvariate(mean, sdev): it is used for the normal distribution where the mu is a mean and the sdev is a sigma that is used for standard deviation.
• The Random class that is used and instantiated creates an independent multiple random number generators.

Q25. What is the difference between range & xrange?

Ans: For the most part, xrange and range are the exact same in terms of functionality. They both provide a way to generate a list of integers for you to use, however you please. The only difference is that range returns a Python list object and x range returns an xrange object.

This means that xrange doesn’t actually generate a static list at run-time like range does. It creates the values as you need them with a special technique called yielding. This technique is used with a type of object known as generators. That means that if you have a really gigantic range you’d like to generate a list for, say one billion, xrange is the function to use.

This is especially true if you have a really memory sensitive system such as a cell phone that you are working with, as range will use as much memory as it can to create your array of integers, which can result in a Memory Error and crash your program. It’s a memory hungry beast.

Q26. How do you write comments in python?

Ans: Comments in Python start with a # character. However, alternatively at times, commenting is done using docstrings(strings enclosed within triple quotes).

Example:

#Comments in Python start like this
print("Comments in Python start with a #")

Output: Comments in Python start with a #

##3 Q27. What is pickling and unpickling?

Ans: Pickle module accepts any Python object and converts it into a string representation and dumps it into a file by using dump function, this process is called pickling. While the process of retrieving original Python objects from the stored string representation is called unpickling.

Q28. What are the generators in python?

Ans: Functions that return an iterable set of items are called generators.

Q29. How will you capitalize the first letter of string?

Ans: In Python, the capitalize() method capitalizes the first letter of a string. If the string already consists of a capital letter at the beginning, then, it returns the original string.

Q30. How will you convert a string to all lowercase?

Ans: To convert a string to lowercase, lower() function can be used.

Example:

stg='ABCD'
print(stg.lower())

Output: abcd

Q31. How to comment multiple lines in python?

Ans: Multi-line comments appear in more than one line. All the lines to be commented are to be prefixed by a #. You can also a very good shortcut method to comment multiple lines. All you need to do is hold the ctrl key and left click in every place wherever you want to include a # character and type a # just once. This will comment all the lines where you introduced your cursor.

Q32.What are docstrings in Python?

Ans: Docstrings are not actually comments, but, they are documentation strings. These docstrings are within triple quotes. They are not assigned to any variable and therefore, at times, serve the purpose of comments as well.

Example:

"""
Using docstring as a comment.
This code divides 2 numbers
"""
x=8
y=4
z=x/y
print(z)

Output: 2.0

Q33. What is the purpose of is, not and in operators?

Ans: Operators are special functions. They take one or more values and produce a corresponding result.

is: returns true when 2 operands are true (Example: “a” is ‘a’)
not: returns the inverse of the boolean value
in: checks if some element is present in some sequence

Q34. What is the usage of help() and dir() function in Python?

Ans: Help() and dir() both functions are accessible from the Python interpreter and used for viewing a consolidated dump of built-in functions.

• Help() function: The help() function is used to display the documentation string and also facilitates you to see the help related to modules, keywords, attributes, etc.
• Dir() function: The dir() function is used to display the defined symbols.

Q35. Whenever Python exits, why isn’t all the memory de-allocated?

Ans:

• Whenever Python exits, especially those Python modules which are having circular references to other objects or the objects that are referenced from the global namespaces are not always de-allocated or freed.
• It is impossible to de-allocate those portions of memory that are reserved by the C library.
• On exit, because of having its own efficient clean up mechanism, Python would try to de-allocate/destroy every other object.

Q36. What is a dictionary in Python?

Ans: The built-in datatypes in Python is called dictionary. It defines one-to-one relationship between keys and values. Dictionaries contain pair of keys and their corresponding values. Dictionaries are indexed by keys.

Let’s take an example:

The following example contains some keys. Country, Capital & PM. Their corresponding values are India, Delhi and Modi respectively.

dict={'Country':'India','Capital':'Delhi','PM':'Modi'}

print dict[Country]

India

print dict[Capital]

Delhi

print dict[PM]

Modi

Q37. How can the ternary operators be used in python?

Ans: The Ternary operator is the operator that is used to show the conditional statements. This consists of the true or false values with a statement that has to be evaluated for it.

Syntax:

The Ternary operator will be given as:
[on_true] if [expression] else [on_false]x, y = 25, 50big = x if x < y else y

Example:

The expression gets evaluated like if x<y else y, in this case if x<y is true then the value is returned as big=x and if it is incorrect then big=y will be sent as a result.

Q38. What does this mean: *args, **kwargs? And why would we use it?

Ans: We use *args when we aren’t sure how many arguments are going to be passed to a function, or if we want to pass a stored list or tuple of arguments to a function. **kwargs is used when we don’t know how many keyword arguments will be passed to a function, or it can be used to pass the values of a dictionary as keyword arguments. The identifiers args and kwargs are a convention, you could also use *bob and **billy but that would not be wise.

Q39. What does len() do?

Ans: It is used to determine the length of a string, a list, an array, etc.

Example:

stg='ABCD'
len(stg)

Q40. Explain split(), sub(), subn() methods of “re” module in Python.

Ans: To modify the strings, Python’s “re” module is providing 3 methods. They are:

• split() – uses a regex pattern to “split” a given string into a list.
• sub() – finds all substrings where the regex pattern matches and then replace them with a different string
• subn() – it is similar to sub() and also returns the new string along with the no. of replacements.

Q41. What are negative indexes and why are they used?

Ans: The sequences in Python are indexed and it consists of the positive as well as negative numbers. The numbers that are positive uses ‘0’ that is uses as first index and ‘1’ as the second index and the process goes on like that.

The index for the negative number starts from ‘-1’ that represents the last index in the sequence and ‘-2’ as the penultimate index and the sequence carries forward like the positive number.

The negative index is used to remove any new-line spaces from the string and allow the string to except the last character that is given as S[:-1]. The negative index is also used to show the index to represent the string in correct order.

Q42. What are Python packages?

Ans: Python packages are namespaces containing multiple modules.

Q43.How can files be deleted in Python?

Ans: To delete a file in Python, you need to import the OS Module. After that, you need to use the os.remove() function.

Example:

import os
os.remove("xyz.txt")

Q44. What are the built-in types of python?

Ans: Built-in types in Python are as follows –

• Integers
• Floating-point
• Complex numbers
• Strings
• Boolean
• Built-in functions

Q45. What advantages do NumPy arrays offer over (nested) Python lists?

Ans:

• Python’s lists are efficient general-purpose containers. They support (fairly) efficient insertion, deletion, appending, and concatenation, and Python’s list comprehensions make them easy to construct and manipulate.
• They have certain limitations: they don’t support “vectorized” operations like elementwise addition and multiplication, and the fact that they can contain objects of differing types mean that Python must store type information for every element, and must execute type dispatching code when operating on each element.
• NumPy is not just more efficient; it is also more convenient. You get a lot of vector and matrix operations for free, which sometimes allow one to avoid unnecessary work. And they are also efficiently implemented.
• NumPy array is faster and You get a lot built in with NumPy, FFTs, convolutions, fast searching, basic statistics, linear algebra, histograms, etc.

Q46. How to add values to a python array?

Ans: Elements can be added to an array using the append(), extend() and the insert (i,x) functions.

Example:

a=arr.array('d', [1.1 , 2.1 ,3.1] )
a.append(3.4)
print(a)
a.extend([4.5,6.3,6.8])
print(a)
a.insert(2,3.8)
print(a)

Output:
array(‘d’, [1.1, 2.1, 3.1, 3.4])
array(‘d’, [1.1, 2.1, 3.1, 3.4, 4.5, 6.3, 6.8])
array(‘d’, [1.1, 2.1, 3.8, 3.1, 3.4, 4.5, 6.3, 6.8])

Q47. How to remove values to a python array?

Ans: Array elements can be removed using pop() or remove() method. The difference between these two functions is that the former returns the deleted value whereas the latter does not.

Example:

a=arr.array('d', [1.1, 2.2, 3.8, 3.1, 3.7, 1.2, 4.6])
print(a.pop())
print(a.pop(3))
a.remove(1.1)
print(a)

Output:
4.6
3.1
array(‘d’, [2.2, 3.8, 3.7, 1.2])

Q48. Does Python have OOps concepts?

Ans: Python is an object-oriented programming language. This means that any program can be solved in python by creating an object model. However, Python can be treated as procedural as well as structural language.

Q49. What is the difference between deep and shallow copy?

Ans: Shallow copy is used when a new instance type gets created and it keeps the values that are copied in the new instance. Shallow copy is used to copy the reference pointers just like it copies the values. These references point to the original objects and the changes made in any member of the class will also affect the original copy of it. Shallow copy allows faster execution of the program and it depends on the size of the data that is used.

Deep copy is used to store the values that are already copied. Deep copy doesn’t copy the reference pointers to the objects. It makes the reference to an object and the new object that is pointed by some other object gets stored. The changes made in the original copy won’t affect any other copy that uses the object. Deep copy makes execution of the program slower due to making certain copies for each object that is been called.

Q50. How is Multithreading achieved in Python?

Ans:

• Python has a multi-threading package but if you want to multi-thread to speed your code up, then it’s usually not a good idea to use it.
• Python has a construct called the Global Interpreter Lock (GIL). The GIL makes sure that only one of your ‘threads’ can execute at any one time. A thread acquires the GIL, does a little work, then passes the GIL onto the next thread.
• This happens very quickly so to the human eye it may seem like your threads are executing in parallel, but they are really just taking turns using the same CPU core.
• All this GIL passing adds overhead to execution. This means that if you want to make your code run faster then using the threading package often isn’t a good idea.

Q51. What is the process of compilation and linking in python?

Ans: The compiling and linking allows the new extensions to be compiled properly without any error and the linking can be done only when it passes the compiled procedure. If the dynamic loading is used then it depends on the style that is being provided with the system. The python interpreter can be used to provide the dynamic loading of the configuration setup files and will rebuild the interpreter.

The steps that are required in this as:

• Create a file with any name and in any language that is supported by the compiler of your system. For example file.c or file.cpp
• Place this file in the Modules/ directory of the distribution which is getting used.
• Add a line in the file Setup.local that is present in the Modules/ directory.
• Run the file using spam file.o
• After a successful run of this rebuild the interpreter by using the make command on the top-level directory.
• If the file is changed then run rebuildMakefile by using the command as ‘make Makefile’.

Q52. What are Python libraries? Name a few of them.

Python libraries are a collection of Python packages. Some of the majorly used python libraries are – Numpy, Pandas, Matplotlib, Scikit-learn and many more.

Q53. What is split used for?

The split() method is used to separate a given string in Python.

Example:

a="morioh python"
print(a.split())

Output: [‘morioh’, ‘python’]

Q54. How to import modules in python?

Modules can be imported using the import keyword. You can import modules in three ways-

Example:

import array           #importing using the original module name
import array as arr    # importing using an alias name
from array import *    #imports everything present in the array module

OOPS Interview Questions

Q55. Explain Inheritance in Python with an example.

Ans: Inheritance allows One class to gain all the members(say attributes and methods) of another class. Inheritance provides code reusability, makes it easier to create and maintain an application. The class from which we are inheriting is called super-class and the class that is inherited is called a derived / child class.

They are different types of inheritance supported by Python:

• Single Inheritance – where a derived class acquires the members of a single super class.
• Multi-level inheritance – a derived class d1 in inherited from base class base1, and d2 are inherited from base2.
• Hierarchical inheritance – from one base class you can inherit any number of child classes
• Multiple inheritance – a derived class is inherited from more than one base class.

Q56. How are classes created in Python?

Ans: Class in Python is created using the class keyword.

Example:

class Employee:
def __init__(self, name):
self.name = name
E1=Employee("abc")
print(E1.name)

Output: abc

Q57. What is monkey patching in Python?

Ans: In Python, the term monkey patch only refers to dynamic modifications of a class or module at run-time.

Consider the below example:

# m.py
class MyClass:
def f(self):
print "f()"

We can then run the monkey-patch testing like this:

import m
def monkey_f(self):
print "monkey_f()"
 
m.MyClass.f = monkey_f
obj = m.MyClass()
obj.f()

The output will be as below:
monkey_f()

As we can see, we did make some changes in the behavior of f() in MyClass using the function we defined, monkey_f(), outside of the module m.

Q58. Does python support multiple inheritance?

Ans: Multiple inheritance means that a class can be derived from more than one parent classes. Python does support multiple inheritance, unlike Java.

Q59. What is Polymorphism in Python?

Ans: Polymorphism means the ability to take multiple forms. So, for instance, if the parent class has a method named ABC then the child class also can have a method with the same name ABC having its own parameters and variables. Python allows polymorphism.

Q60. Define encapsulation in Python?

Ans: Encapsulation means binding the code and the data together. A Python class in an example of encapsulation.

Q61. How do you do data abstraction in Python?

Ans: Data Abstraction is providing only the required details and hiding the implementation from the world. It can be achieved in Python by using interfaces and abstract classes.

Q62.Does python make use of access specifiers?

Ans: Python does not deprive access to an instance variable or function. Python lays down the concept of prefixing the name of the variable, function or method with a single or double underscore to imitate the behavior of protected and private access specifiers.

Q63. How to create an empty class in Python?

Ans: An empty class is a class that does not have any code defined within its block. It can be created using the pass keyword. However, you can create objects of this class outside the class itself. IN PYTHON THE PASS command does nothing when its executed. it’s a null statement.

For example-

class a:
    pass
obj=a()
obj.name="xyz"
print("Name = ",obj.name)

Output:
Name = xyz

Q64. What does an object() do?

Ans: It returns a featureless object that is a base for all classes. Also, it does not take any parameters.

Basic Python Programs

Q65. Write a program in Python to execute the Bubble sort algorithm.

def bs(a):             # a = name of list
    b=len(a)-1         # minus 1 because we always compare 2 adjacent values
                             
    for x in range(b):
        for y in range(b-x):
            if a[y]>a[y+1]:
                a[y],a[y+1]=a[y+1],a[y]
    return a
a=[32,5,3,6,7,54,87]
bs(a)

Output: [3, 5, 6, 7, 32, 54, 87]

Q66. Write a program in Python to produce Star triangle.

def pyfunc(r):
    for x in range(r):
        print(' '*(r-x-1)+'*'*(2*x+1))    
pyfunc(9)

Output:

    *
   ***
  *****
 *******
*********

---

---

---

---

Q67. Write a program to produce Fibonacci series in Python.

# Enter number of terms needed                   #0,1,1,2,3,5....
a=int(input("Enter the terms"))
f=0                                         #first element of series
s=1                                         #second element of series
if a<=0:
    print("The requested series is
",f)
else:
    print(f,s,end=" ")
    for x in range(2,a):
        next=f+s                           
        print(next,end=" ")
        f=s
        s=next</pre>

Output: Enter the terms 5 0 1 1 2 3

Q68. Write a program in Python to check if a number is prime.

a=int(input("enter number"))     
if a>1:
    for x in range(2,a):
        if(a%x)==0:
            print("not prime")
            break
    else:
        print("Prime")
else:
    print("not prime")

Output:
enter number 3
Prime

Q69. Write a program in Python to check if a sequence is a Palindrome.

a=input("enter sequence")
b=a[::-1]
if a==b:
    print("palindrome")
else:
    print("Not a Palindrome")

Output:
enter sequence 323 palindrome

Q70. Write a one-liner that will count the number of capital letters in a file. Your code should work even if the file is too big to fit in memory.

Ans: Let us first write a multiple line solution and then convert it to one-liner code.

with open(SOME_LARGE_FILE) as fh:
count = 0
text = fh.read()
for character in text:
    if character.isupper():
count += 1

We will now try to transform this into a single line.

count sum(1 for line in fh for character in line if character.isupper())

Q71. Write a sorting algorithm for a numerical dataset in Python.

Ans: The following code can be used to sort a list in Python:

list = ["1", "4", "0", "6", "9"]
list = [int(i) for i in list]
list.sort()
print (list)

Q72. Looking at the below code, write down the final values of A0, A1, …An.

A0 = dict(zip(('a','b','c','d','e'),(1,2,3,4,5)))
A1 = range(10)A2 = sorted([i for i in A1 if i in A0])
A3 = sorted([A0[s] for s in A0])
A4 = [i for i in A1 if i in A3]
A5 = {i:i*i for i in A1}
A6 = [[i,i*i] for i in A1]
print(A0,A1,A2,A3,A4,A5,A6)

Ans: The following will be the final outputs of A0, A1, … A6

A0 = {‘a’: 1, ‘c’: 3, ‘b’: 2, ‘e’: 5, ‘d’: 4} # the order may vary
A1 = range(0, 10)
A2 = []
A3 = [1, 2, 3, 4, 5]
A4 = [1, 2, 3, 4, 5]
A5 = {0: 0, 1: 1, 2: 4, 3: 9, 4: 16, 5: 25, 6: 36, 7: 49, 8: 64, 9: 81}
A6 = [[0, 0], [1, 1], [2, 4], [3, 9], [4, 16], [5, 25], [6, 36], [7, 49], [8, 64], [9, 81]]

Python Libraries Interview Questions

Q73. Explain what Flask is and its benefits?

Ans: Flask is a web microframework for Python based on “Werkzeug, Jinja2 and good intentions” BSD license. Werkzeug and Jinja2 are two of its dependencies. This means it will have little to no dependencies on external libraries. It makes the framework light while there is a little dependency to update and fewer security bugs.

A session basically allows you to remember information from one request to another. In a flask, a session uses a signed cookie so the user can look at the session contents and modify. The user can modify the session if only it has the secret key Flask.secret_key.

Q74. Is Django better than Flask?

Ans: Django and Flask map the URL’s or addresses typed in the web browsers to functions in Python.

Flask is much simpler compared to Django but, Flask does not do a lot for you meaning you will need to specify the details, whereas Django does a lot for you wherein you would not need to do much work. Django consists of prewritten code, which the user will need to analyze whereas Flask gives the users to create their own code, therefore, making it simpler to understand the code. Technically both are equally good and both contain their own pros and cons.

Q75. Mention the differences between Django, Pyramid and Flask.

Ans:

• Flask is a “microframework” primarily build for a small application with simpler requirements. In flask, you have to use external libraries. Flask is ready to use.
• Pyramid is built for larger applications. It provides flexibility and lets the developer use the right tools for their project. The developer can choose the database, URL structure, templating style and more. Pyramid is heavy configurable.
• Django can also be used for larger applications just like Pyramid. It includes an ORM.

Q76. Discuss Django architecture.

Ans: Django MVT Pattern:

The developer provides the Model, the view and the template then just maps it to a URL and Django does the magic to serve it to the user.

Q77. Explain how you can set up the Database in Django.

Ans: You can use the command edit mysite/setting.py, it is a normal python module with module level representing Django settings.

Django uses SQLite by default; it is easy for Django users as such it won’t require any other type of installation. In the case your database choice is different that you have to the following keys in the DATABASE ‘default’ item to match your database connection settings.

• Engines: you can change the database by using ‘django.db.backends.sqlite3’ , ‘django.db.backeneds.mysql’, ‘django.db.backends.postgresql_psycopg2’, ‘django.db.backends.oracle’ and so on
• Name: The name of your database. In the case if you are using SQLite as your database, in that case, database will be a file on your computer, Name should be a full absolute path, including the file name of that file.
• If you are not choosing SQLite as your database then settings like Password, Host, User, etc. must be added.

Django uses SQLite as a default database, it stores data as a single file in the filesystem. If you do have a database server—PostgreSQL, MySQL, Oracle, MSSQL—and want to use it rather than SQLite, then use your database’s administration tools to create a new database for your Django project. Either way, with your (empty) database in place, all that remains is to tell Django how to use it. This is where your project’s settings.py file comes in.

We will add the following lines of code to the setting.py file:

DATABASES = {
     'default': {
          'ENGINE' : 'django.db.backends.sqlite3',
          'NAME' : os.path.join(BASE_DIR, 'db.sqlite3'),
     }
}

Q78. Give an example how you can write a VIEW in Django?

Ans: This is how we can use write a view in Django:

from django.http import HttpResponse
import datetime
 
def Current_datetime(request):
     now = datetime.datetime.now()
     html = "<html><body>It is now %s</body></html> % now
     return HttpResponse(html)

Returns the current date and time, as an HTML document

Q79. Mention what the Django templates consist of.

Ans: The template is a simple text file. It can create any text-based format like XML, CSV, HTML, etc. A template contains variables that get replaced with values when the template is evaluated and tags (% tag %) that control the logic of the template.

Q80. Explain the use of session in Django framework?

Ans: Django provides a session that lets you store and retrieve data on a per-site-visitor basis. Django abstracts the process of sending and receiving cookies, by placing a session ID cookie on the client side, and storing all the related data on the server side.

So the data itself is not stored client side. This is nice from a security perspective.

Q81. List out the inheritance styles in Django.

Ans: In Django, there are three possible inheritance styles:

• Abstract Base Classes: This style is used when you only want parent’s class to hold information that you don’t want to type out for each child model.
• Multi-table Inheritance: This style is used If you are sub-classing an existing model and need each model to have its own database table.
• Proxy models: You can use this model, If you only want to modify the Python level behavior of the model, without changing the model’s fields.

Web Scraping – Python Interview Questions

Q82. How To Save An Image Locally Using Python Whose URL Address I Already Know?

Ans: We will use the following code to save an image locally from an URL address

import urllib.request
urllib.request.urlretrieve("URL", "local-filename.jpg")

Q83. How can you Get the Google cache age of any URL or web page?

Ans: Use the following URL format:

http://webcache.googleusercontent.com/search?q=cache:URLGOESHERE

Be sure to replace “URLGOESHERE” with the proper web address of the page or site whose cache you want to retrieve and see the time for. For example, to check the Google Webcache age of edureka.co you’d use the following URL:

http://webcache.googleusercontent.com/search?q=cache:edureka.co

Q84. You are required to scrap data from IMDb top 250 movies page. It should only have fields movie name, year, and rating.

Ans: We will use the following lines of code:

from bs4 import BeautifulSoup
 
import requests
import sys
 
url = '<a href="http://www.imdb.com/chart/top">http://www.imdb.com/chart/top</a>'
response = requests.get(url)
soup = BeautifulSoup(response.text)
tr = soup.findChildren("tr")
tr = iter(tr)
next(tr)
 
for movie in tr:
title = movie.find('td', {'class': 'titleColumn'} ).find('a').contents[0]
year = movie.find('td', {'class': 'titleColumn'} ).find('span', {'class': 'secondaryInfo'}).contents[0]
rating = movie.find('td', {'class': 'ratingColumn imdbRating'} ).find('strong').contents[0]
row = title + ' - ' + year + ' ' + ' ' + rating
 
print(row)

The above code will help scrap data from IMDb’s top 250 list

Data Analysis – Python Interview Questions

Q85. What is map function in Python?

Ans: map function executes the function given as the first argument on all the elements of the iterable given as the second argument. If the function given takes in more than 1 arguments, then many iterables are given. #Follow the link to know more similar functions.

Q86. Is python numpy better than lists?

Ans: We use python numpy array instead of a list because of the below three reasons:

• Less Memory
• Fast
• Convenient

For more information on these parameters, you can refer to this section – Numpy Vs List.

Q87. How to get indices of N maximum values in a NumPy array?

Ans: We can get the indices of N maximum values in a NumPy array using the below code:

import numpy as np
arr = np.array([1, 3, 2, 4, 5])
print(arr.argsort()[-3:][::-1])

Output
[ 4 3 1 ]

Q88. How do you calculate percentiles with Python/ NumPy?

Ans: We can calculate percentiles with the following code

import numpy as np
a = np.array([1,2,3,4,5])
p = np.percentile(a, 50) #Returns 50th percentile, e.g. median
print(p)

Output
3

Q89. What is the difference between NumPy and SciPy?

Ans:

• In an ideal world, NumPy would contain nothing but the array data type and the most basic operations: indexing, sorting, reshaping, basic elementwise functions, et cetera.
• All numerical code would reside in SciPy. However, one of NumPy’s important goals is compatibility, so NumPy tries to retain all features supported by either of its predecessors.
• Thus NumPy contains some linear algebra functions, even though these more properly belong in SciPy. In any case, SciPy contains more fully-featured versions of the linear algebra modules, as well as many other numerical algorithms.
• If you are doing scientific computing with python, you should probably install both NumPy and SciPy. Most new features belong in SciPy rather than NumPy.

Q90. How do you make 3D plots/visualizations using NumPy/SciPy?

Ans: Like 2D plotting, 3D graphics is beyond the scope of NumPy and SciPy, but just as in the 2D case, packages exist that integrate with NumPy. Matplotlib provides basic 3D plotting in the mplot3d subpackage, whereas Mayavi provides a wide range of high-quality 3D visualization features, utilizing the powerful VTK engine.

Multiple Choice Questions (MCQ)

Q91. Which of the following statements create a dictionary? (Multiple Correct Answers Possible)

a) d = {}
b) d = {“john”:40, “peter”:45}
c) d = {40:”john”, 45:”peter”}
d) d = (40:”john”, 45:”50”)

Answer: b, c & d.

Dictionaries are created by specifying keys and values.

Q92. Which one of these is floor division?

a) /
b) //
c) %
d) None of the mentioned

Answer: b) //

When both of the operands are integer then python chops out the fraction part and gives you the round off value, to get the accurate answer use floor division. For ex, 5/2 = 2.5 but both of the operands are integer so answer of this expression in python is 2. To get the 2.5 as the answer, use floor division using //. So, 5//2 = 2.5

Q93. What is the maximum possible length of an identifier?

a) 31 characters
b) 63 characters
c) 79 characters
d) None of the above

Answer: d) None of the above

Identifiers can be of any length.

Q94. Why are local variable names beginning with an underscore discouraged?

a) they are used to indicate a private variables of a class
b) they confuse the interpreter
c) they are used to indicate global variables
d) they slow down execution

Answer: a) they are used to indicate a private variable of a class

As Python has no concept of private variables, leading underscores are used to indicate variables that must not be accessed from outside the class.

Q95. Which of the following is an invalid statement?

a) abc = 1,000,000
b) a b c = 1000 2000 3000
c) a,b,c = 1000, 2000, 3000
d) a_b_c = 1,000,000

Answer: b) a b c = 1000 2000 3000

Spaces are not allowed in variable names.

Q96. What is the output of the following?

try:
    if '1' != 1:
        raise "someError"
    else:
        print("someError has not occured")
except "someError":
    print ("someError has occured")

a) someError has occured
b) someError has not occured
c) invalid code
d) none of the above

Answer: c) invalid code

A new exception class must inherit from a BaseException. There is no such inheritance here.

Q97. Suppose list1 is [2, 33, 222, 14, 25], What is list1[-1] ?

a) Error
b) None
c) 25
d) 2

Answer: c) 25

The index -1 corresponds to the last index in the list.

Q98. To open a file c:scores.txt for writing, we use

a) outfile = open(“c:scores.txt”, “r”)
b) outfile = open(“c:scores.txt”, “w”)
c) outfile = open(file = “c:scores.txt”, “r”)
d) outfile = open(file = “c:scores.txt”, “o”)

Answer: b) The location contains double slashes ( ) and w is used to indicate that file is being written to.

Q99. What is the output of the following?

f = None
 
for i in range (5):
    with open("data.txt", "w") as f:
        if i > 2:
            break
 
print f.closed

a) True
b) False
c) None
d) Error

Answer: a) True

The WITH statement when used with open file guarantees that the file object is closed when the with block exits.

Q100. When will the else part of try-except-else be executed?

a) always
b) when an exception occurs
c) when no exception occurs
d) when an exception occurs into except block

Answer: c) when no exception occurs

The else part is executed when no exception occurs.

I hope this set of Python Interview Questions will help you in preparing for your interviews. All the best!

Originally published at https://www.edureka.co

#python #interview #interview-questions

What is GEEK

Buddha Community

top 30 Python Tips and Tricks for Beginners

Welcome to my Blog , In this article, you are going to learn the top 10 python tips and tricks.

1) swap two numbers.

2) Reversing a string in Python.

3) Create a single string from all the elements in list.

4) Chaining Of Comparison Operators.

5) Print The File Path Of Imported Modules.

6) Return Multiple Values From Functions.

7) Find The Most Frequent Value In A List.

8) Check The Memory Usage Of An Object.

…

#python #python hacks tricks #python learning tips #python programming tricks #python tips #python tips and tricks #python tips and tricks advanced #python tips and tricks for beginners #python tips tricks and techniques #python tutorial #tips and tricks in python #tips to learn python #top 30 python tips and tricks for beginners

Top 130 Android Interview Questions - Crack Technical Interview Now!

Android Interview Questions and Answers from Beginner to Advanced level

DataFlair is committed to provide you all the resources to make you an android professional. We started with android tutorials along with practicals, then we published Real-time android projects along with source code. Now, we come up with frequently asked android interview questions, which will help you in showing expertise in your next interview.

Android Interview Questions – Get ready for your next interview

Android – one of the hottest technologies, which is having a bright future. Get ready to crack your next interview with the following android interview questions. These interview questions start with basic and cover deep concepts along with advanced topics.

Android Interview Questions for Freshers

1. What is Android?

Android is an open-source mobile operating system that is based on the modified versions of Linux kernel. Though it was mainly designed for smartphones, now it is being used for Tablets, Televisions, Smartwatches, and other Android wearables.

2. Who is the inventor of Android Technology?

The inventors of Android Technology are- Andry Rubin, Nick Sears, and Rich Miner.

3. What is the latest version of Android?

The latest version of Android is Android 10.0, known as Android Q. The upcoming major Android release is Android 11, which is the 18th version of Android. [Note: Keep checking the versions, it is as of June 2020.]

4. How many Android versions can you recall right now?

Till now, there are 17 versions of Android, which have their names in alphabetical order. The 18th version of Android is also going to come later this year. The versions of Android are here:

• Android 1.0 – Its release is 23 September 2008.
• Android 1.1 – Its release date is 9 February 2009.
• Android 1.5 – Its name is Cupcake, Released on 27 April 2009.
• Android 1.6 – Its name is Donut, Released on 15 September 2009.
• Android 2.0 – Its name is Eclair, Released on 26 October 2009
• Android 2.2 – Its name is Froyo, Released on 20 May 2010.
• Android 2.3 – Its name is Gingerbread, Released on 06 December 2010.
• Android 3.0 – Its name is Honeycomb, Released on 22 February 2011.
• Android 4.0 – Its name is Ice Cream Sandwich, Released on 18 October 2011.
• Android 4.1 – Its name is Jelly Bean, Released on 9 July 2012.
• Android 4.4 – Its name is KitKat, Released on 31 October 2013.
• Android 5.0 – Its name is Lollipop, Released on 12 November 2014.
• Android 6.0 – Its name is Marshmallow, Released on 5 October 2015.
• Android 7.0 – Its name is Nougat, Released on 22 August 2016.
• Android 8.0 – Its name is Oreo, Released on 21 August 2017.
• Android 9.0 – Its name is Pie, Released on 6 August 2018.
• Android 10.0 – Its name is Android Q, Released on 3 September 2019.
• Android 11.0 – As of now, it is Android 11.

5. Explain the Android Architecture with its components.

This is a popular android developer interview question

Android Architecture consists of 5 components that are-

a. Linux Kernel: It is the foundation of the Android Architecture that resides at the lowest level. It provides the level of abstraction for hardware devices and upper layer components. Linux Kernel also provides various important hardware drivers that act as software interfaces for hardwares like camera, bluetooth, etc.

b. Native Libraries: These are the libraries for Android that are written in C/C++. These libraries are useful to build many core services like ART and HAL. It provides support for core features.

c. Android Runtime: It is an Android Runtime Environment. Android Operating System uses it during the execution of the app. It performs the translation of the application bytecode into the native instructions. The runtime environment of the device then executes these native instructions.

d. Application Framework: Application Framework provides many java classes and interfaces for app development. And it also provides various high-level services. This complete Application framework makes use of Java.

e. Applications: This is the topmost layer of Android Architecture. It provides applications for the end-user, so they can use the android device and compute the tasks.

6. What are the services that the Application framework provides?

The Android application framework has the following key services-

a. Activity Manager: It uses testing and debugging methods.

b. Content provider: It provides the data from application to other layers.

c. Resource Manager: This provides users access to resources.

d. Notification Manager: This gives notification to the users regarding actions taking place in the background.

e. View System: It is the base class for widgets, and it is also responsible for event handling.

7. What are the important features of Linux Kernel?

The important features of the Linux Kernel are as follows:

a. Power Management: Linux Kernel does power management to enhance and improve the battery life of the device.

b. Memory Management: It is useful for the maximum utilization of the available memory of the device.

c. Device Management: It includes managing all the hardware device drivers. It maximizes the utilization of the available resources.

d. Security: It ensures that no application has any such permission that it affects any other application in order to maintain security.

e. Multi-tasking: Multi-tasking provides the users the ease of doing multiple tasks at the same time.

8. What are the building blocks of an Android Application?

This is a popular android interview question for freshers.

The main components of any Android application are- Activity, Services, Content Provider, and Broadcast Receiver. You can understand them as follows:

a. Activity- It is a class that acts as the entry point representing a single screen to the user. It is like a window to show the user interface.

b. Services- Services are the longest-running component that runs in the background.

c. Content Provider- The content provider is an essential component that allows apps to share data between themselves.

d. Broadcast receivers- Broadcast receiver is another most crucial application component. It helps the apps to receive and respond to broadcast messages from the system or some other application.

9. What are the important components of Android Application?

The Components of Android application are listed below:

1. Widgets
2. Intents
3. Views
4. Notification
5. Fragments
6. Layout XML files
7. Resources

10. What are the widgets?

Widgets are the variations of Broadcast receivers. They are an important part of home screen customization. They often display some data and also allow users to perform actions on them. Mostly they display the app icon on the screen.

11. Can you name some types of widgets?

Mentioned below are the types of widgets-

a. Informative Widgets: These widgets show some important information. Like, the clock widget or a weather widget.

b. Collective Widgets: They are the collection of some types of elements. For example, a music widget that lets us change, skip, or forward the song.

c. Control Widgets: These widgets help us control the actions within the application through it. Like an email widget that helps check the recent mails.

d. Hybrid Widgets: Hybrid widgets are those that consist of at least two or more types of widgets.

12. What are Intents?

Intents are an important part of Android Applications. They enable communication between components of the same application as well as separate applications. The Intent signals the Android system about a certain event that has occurred.

13. Explain the types of intents briefly?

Intent is of three types that are-

a. Implicit Intents: Implicit intents are those in which there is no description of the component name but only the action.

b. Explicit Intents: In explicit intents, the target component is present by declaring the name of the component.

c. Pending Intents: These are those intents that act as a shield over the Intent objects. It covers the intent objects and grants permission to the external app components to access them.

14. What is a View?

A view is an important building block that helps in designing the user interface of the application. It can be a rectangular box or a circular shape, for example, Text View, Edit Text, Buttons, etc. Views occupy a certain area of the screen, and it is also responsible for event handling. A view is the superclass of all the graphical user interface components.

15. What do you understand by View Group?

It is the subclass of the ViewClass. It gives an invisible container to hold layouts or views. You can understand view groups as special views that are capable of holding other views, that are Child View.

16. What do you understand about Shared Preferences?

It is a simple mechanism for data storage in Android. In this, there is no need to create files, and using APIs, it stores the data in XML files. It stores the data in the pair of key-values. SharedPreferences class lets the user save the values and retrieve them when required. Using SharedPreferences we can save primitive data like- boolean, float, integer, string and long.

17. What is a Notification?

A notification is just like a message that shows up outside the Application UI to provide reminders to the users. They remind the user about a message received, or some other timely information from the app.

18. Give names of Notification types.

There are three types of notifications namely-

a. Toast Notification- This notification is the one that fades away sometime after it pops up.

b. Status Notification- This notification stays till the user takes some action on it.

c. Dialog Notification- This notification is the result of an Active Activity.

19. What are fragments?

A fragment is a part of the complete user interface. These are present in Activity, and an activity can have one or more fragments at the same time. We can reuse a fragment in multiple activities as well.

20. What are the types of fragments?

There are three types of fragments that are: Single Fragment, List Fragment, Fragment Transactions.

1. Single Transactions can only show a single view for the user.
2. List Fragments have a special list view feature that provides a list from which the user can select one.
3. Fragment Transactions are helpful for the transition between one fragment to the other.

Frequently asked Android Interview Questions and Answers

21. What are Layout XML files?

Layout XML files contain the structure for the user interface of the application. The XML file also contains various different layouts and views, and they also specify various GUI components that are there in Activity or fragments.

22. What are Resources in Android Application?

The resources in Android Apps defines images, texts, strings, colors, etc. Everything in resources directory is referenced in the source code of the app so that we can use them.

23. Can you develop Android Apps with languages other than Java? If so, name some.

Yes, there are many languages that we can work with, for the development of Android Applications. To name some, I would say Java, Python, C, C++, Kotlin, C#, Corona/LUA.

24. What are the states of the Activity Lifecycle?

Activity lifecycle has the following four stages-

a. Running State: As soon as the activity starts, it is the first state.

b. Paused State: When some other activity starts without closing the previous one, the running activity turns into the Paused state.

c. Resume State: When the activity opens again after being in pause state, it comes into the Resume State.

d. Stopped State: When the user closes the application or stops using it, the activity goes to the Stopped state.

25. What are some methods of Activity?

The methods of Activity are as follows:

• onCreate()
• onStart()
• onPause()
• onRestart()
• onResume()
• onStop()
• onDestroy()

26. How can you launch an activity in Android?

We launch an activity using Intents. For this we need to use intent as follows:

1. ntent intent_name= new Intent(this, Activity_name.class);
2. startActivity(intent_name);

27. What is the service lifecycle?

There are two states of a service that are-

a. Started State: This is when the service starts its execution. A Services come in start state only through the startService() method.

b. Bounded State: A service is in the bounded state when it calls the method bindService().

28. What are some methods of Services?

The methods of service are as follows-

• onStartCommand()
• onBind()
• onCreate()
• onUnbind()
• onDestroy()
• onRebind()

29. What are the types of Broadcast?

Broadcasts are of two types that are-

a. Ordered Broadcast: Ordered broadcasts are Synchronous and work in a proper order. It decides the order by using the priority assigned to the broadcasts.

b. Normal Broadcast: These are asynchronous and unordered. They are more efficient as they run unorderly and all at once. But, they lack full utilization of the results.

30. What are useful impotent folders in Android?

The impotent folders in an Android application are-

1. build.xml- It is responsible for the build of Android applications.
2. bin/ – The bin folder works as a staging area to wrap the files packages into the APK.
3. src/ – The src is a folder where all the source files of the project are present.
4. res/ – The res is the resource folder that stores values of the resources that are used in the application. These resources can be colors, styles, strings, dimensions, etc.
5. assets/ – It provides a facility to include files like text, XML, fonts, music, and video in the Android application.

31. What are the important files for Android Application when working on Android Studio?

This is an important android studio interview question

There are following three files that we need to work on for an application to work-

a. The AndroidManifest.xml file: It has all the information about the application.

b. The MainActivity.java file: It is the app file that actually gets converted to the dalvik executable and runs the application. It is written in java.

c. The Activity_main.xml file: It is the layout file that is available in the res/layout directory. It is another mostly used file while developing the application.

32. Which database do you use for Android Application development?

The database that we use for Android Applications is SQLite. It is because SQLite is lightweight and specially developed for Android Apps. SQLite works the same way as SQL using the same commands.

33. Tell us some features of Android OS.

The best features of Android include-

1. Multi-tasking
2. Support for a great range of languages
3. Support for split-screen
4. High connectivity with 5G support
5. Motion Control

34. Why did you learn Android development?

Learning Android Studio is a good idea because of the following-

1. It has a low application development cost.
2. It is an open-source platform.
3. It has multi-platform support as well as Multi-carrier support.
4. It is open for customizations.
5. Android is a largely used operating system throughout the world.

35. What are the different ways of storage supported in Android?

The various storage ways supported in Android are as follows:

1. Shared Preference
2. Internal Storage
3. External Storage
4. SQLite Databases
5. Network Connection

36. What are layouts?

Layout is nothing but arrangements of elements on the device screen. These elements can be images, tests, videos, anything. They basically define the structure of the Android user interface to make it user friendly.

37. How many layout types are there?

The type of layouts used in Android Apps are as follows:

1. Linear Layout
2. Relative Layout
3. Constraint Layout
4. Table Layout
5. Frame Layout
6. Absolute Layout
7. Scrollview layout

38. What is an APK?

An APK stands for Android Package that is a file format of Android Applications. Android OS uses this package for the distribution and installation of the Android Application.

39. What is an Android Manifest file?

The manifest file describes all the essential information about the project application for build tools, Android operating system, and google play. This file is a must for every Android project that we develop, and it is present in the root of the project source set.

#android tutorials #android basic interview questions #android basic questions #android developer interview questions #android interview question and answer #android interview questions #android interview questions for experienced #android interview questions for fresher

Top 100 Python Interview Questions You Must Prepare in 2020

In this Python Interview Questions tutorial, I will introduce you to the most frequently asked questions in Python interviews. Our Python Interview Questions is the one-stop resource from where you can boost your interview preparation. We have 100+ questions on Python Programming basics which will help you with different expertise levels to reap the maximum benefit from our blog.

Let us start by taking a look at some of the most frequently asked Python interview questions,

Q1. What is the difference between list and tuples in Python?
Q2. What are the key features of Python?
Q3. What type of language is python?
Q4. How is Python an interpreted language?
Q5. What is pep 8?
Q6. How is memory managed in Python?
Q7. What is name space in Python?
Q8. What is PYTHON PATH?
Q9. What are python modules?
Q10. What are local variables and global variables in Python?

We have compiled a list of top Python interview questions which are classified into 7 sections, namely:

• Basic Interview Questions
• OOPS Interview Questions
• Basic Python Programs
• Python Libraries Interview Questions
• Web Scraping Interview Questions
• Data Analysis Interview Questions
• Multiple Choice Questions (MCQ)

Basic Python Interview Questions

Q1. What is the difference between list and tuples in Python?

Q2. What are the key features of Python?

• Python is an interpreted language. That means that, unlike languages like C and its variants, Python does not need to be compiled before it is run. Other interpreted languages include PHP and Ruby.
• Python is dynamically typed, this means that you don’t need to state the types of variables when you declare them or anything like that. You can do things like x=111 and then x=“I’m a string” without error
• Python is well suited to object orientated programming in that it allows the definition of classes along with composition and inheritance. Python does not have access specifiers (like C++’s public, private).
• In Python, functions are first-class objects. This means that they can be assigned to variables, returned from other functions and passed into functions. Classes are also first class objects
• Writing Python code is quick but running it is often slower than compiled languages. Fortunately，Python allows the inclusion of C based extensions so bottlenecks can be optimized away and often are. The numpy package is a good example of this, it’s really quite quick because a lot of the number crunching it does isn’t actually done by Python
• Python finds use in many spheres – web applications, automation, scientific modeling, big data applications and many more. It’s also often used as “glue” code to get other languages and components to play nice.

Q3. What type of language is python? Programming or scripting?

Ans: Python is capable of scripting, but in general sense, it is considered as a general-purpose programming language. To know more about Scripting, you can refer to the Python Scripting Tutorial.

Q4.How is Python an interpreted language?

Ans: An interpreted language is any programming language which is not in machine level code before runtime. Therefore, Python is an interpreted language.

Q5.What is pep 8?

Ans: PEP stands for Python Enhancement Proposal. It is a set of rules that specify how to format Python code for maximum readability.

Q6. How is memory managed in Python?

Ans:

• Memory management in python is managed by Python private heap space. All Python objects and data structures are located in a private heap. The programmer does not have access to this private heap. The python interpreter takes care of this instead.
• The allocation of heap space for Python objects is done by Python’s memory manager. The core API gives access to some tools for the programmer to code.
• Python also has an inbuilt garbage collector, which recycles all the unused memory and so that it can be made available to the heap space.

Q7. What is namespace in Python?

Ans: A namespace is a naming system used to make sure that names are unique to avoid naming conflicts.

Q8. What is PYTHONPATH?

Ans: It is an environment variable which is used when a module is imported. Whenever a module is imported, PYTHONPATH is also looked up to check for the presence of the imported modules in various directories. The interpreter uses it to determine which module to load.

Q9. What are python modules? Name some commonly used built-in modules in Python?

Ans: Python modules are files containing Python code. This code can either be functions classes or variables. A Python module is a .py file containing executable code.

Some of the commonly used built-in modules are:

• os
• sys
• math
• random
• data time
• JSON

Q10.What are local variables and global variables in Python?

Global Variables:

Variables declared outside a function or in global space are called global variables. These variables can be accessed by any function in the program.

Local Variables:

Any variable declared inside a function is known as a local variable. This variable is present in the local space and not in the global space.

Example:

a=2
def add():
b=3
c=a+b
print(c)
add()

Output: 5

When you try to access the local variable outside the function add(), it will throw an error.

Q11. Is python case sensitive?

Ans: Yes. Python is a case sensitive language.

Q12.What is type conversion in Python?

Ans: Type conversion refers to the conversion of one data type iinto another.

int() – converts any data type into integer type
float() – converts any data type into float type
ord() – converts characters into integer
hex() – converts integers to hexadecimal
oct() – converts integer to octal
tuple() – This function is used to convert to a tuple.
set() – This function returns the type after converting to set.
list() – This function is used to convert any data type to a list type.
dict() – This function is used to convert a tuple of order (key,value) into a dictionary.
str() – Used to convert integer into a string.
complex(real,imag) – This functionconverts real numbers to complex(real,imag) number.

Q13. How to install Python on Windows and set path variable?

Ans: To install Python on Windows, follow the below steps:

• Install python from this link: https://www.python.org/downloads/
• After this, install it on your PC. Look for the location where PYTHON has been installed on your PC using the following command on your command prompt: cmd python.
• Then go to advanced system settings and add a new variable and name it as PYTHON_NAME and paste the copied path.
• Look for the path variable, select its value and select ‘edit’.
• Add a semicolon towards the end of the value if it’s not present and then type %PYTHON_HOME%

Q14. Is indentation required in python?

Ans: Indentation is necessary for Python. It specifies a block of code. All code within loops, classes, functions, etc is specified within an indented block. It is usually done using four space characters. If your code is not indented necessarily, it will not execute accurately and will throw errors as well.

Q15. What is the difference between Python Arrays and lists?

Ans: Arrays and lists, in Python, have the same way of storing data. But, arrays can hold only a single data type elements whereas lists can hold any data type elements.

Example:

import array as arr
My_Array=arr.array('i',[1,2,3,4])
My_list=[1,'abc',1.20]
print(My_Array)
print(My_list)

Output:
array(‘i’, [1, 2, 3, 4]) [1, ‘abc’, 1.2]

Q16. What are functions in Python?

Ans: A function is a block of code which is executed only when it is called. To define a Python function, the def keyword is used.

Example:

def Newfunc():
print("Hi, Welcome to Morioh")
Newfunc(); #calling the function

Output: Hi, Welcome to Morioh

Q17.What is init?

Ans: init is a method or constructor in Python. This method is automatically called to allocate memory when a new object/ instance of a class is created. All classes have the init method.

Here is an example of how to use it.

class Employee:
def __init__(self, name, age,salary):
self.name = name
self.age = age
self.salary = 20000
E1 = Employee("XYZ", 23, 20000)
# E1 is the instance of class Employee.
#__init__ allocates memory for E1. 
print(E1.name)
print(E1.age)
print(E1.salary)

Output:
XYZ
23
20000

Q18.What is a lambda function?

Ans: An anonymous function is known as a lambda function. This function can have any number of parameters but, can have just one statement.

Example:

a = lambda x,y : x+y
print(a(5, 6))

Output: 11

Q19. What is self in Python?

Ans: Self is an instance or an object of a class. In Python, this is explicitly included as the first parameter. However, this is not the case in Java where it’s optional. It helps to differentiate between the methods and attributes of a class with local variables.

The self variable in the init method refers to the newly created object while in other methods, it refers to the object whose method was called.

Q20. How does break, continue and pass work?

Q21. What does (::-1} do?

Ans: [::-1] is used to reverse the order of an array or a sequence.
For example:

import array as arr
My_Array=arr.array('i',[1,2,3,4,5])
My_Array[::-1]

Output: array(‘i’, [5, 4, 3, 2, 1])
[::-1] reprints a reversed copy of ordered data structures such as an array or a list. the original array or list remains unchanged.

Q22. How can you randomize the items of a list in place in Python?

Ans: Consider the example shown below:

from random import shuffle
x = ['Keep', 'The', 'Blue', 'Flag', 'Flying', 'High']
shuffle(x)
print(x)

The output of the following code is as below.

[‘Flying’, ‘Keep’, ‘Blue’, ‘High’, ‘The’, ‘Flag’]

Q23. What are python iterators?

Ans: Iterators are objects which can be traversed though or iterated upon.

Q24. How can you generate random numbers in Python?

Ans: Random module is the standard module that is used to generate a random number. The method is defined as:

import random
random.random

The statement random.random() method return the floating point number that is in the range of (0, 1). The function generates random float numbers. The methods that are used with the random class are the bound methods of the hidden instances. The instances of the Random can be done to show the multi-threading programs that creates a different instance of individual threads. The other random generators that are used in this are:

• randrange(a, b): it chooses an integer and define the range in-between (a, b). It returns the elements by selecting it randomly from the range that is specified. It doesn’t build a range object.
• uniform(a, b): it chooses a floating point number that is defined in the range of (a,b).Iyt returns the floating point number
• normalvariate(mean, sdev): it is used for the normal distribution where the mu is a mean and the sdev is a sigma that is used for standard deviation.
• The Random class that is used and instantiated creates an independent multiple random number generators.

Q25. What is the difference between range & xrange?

Ans: For the most part, xrange and range are the exact same in terms of functionality. They both provide a way to generate a list of integers for you to use, however you please. The only difference is that range returns a Python list object and x range returns an xrange object.

This means that xrange doesn’t actually generate a static list at run-time like range does. It creates the values as you need them with a special technique called yielding. This technique is used with a type of object known as generators. That means that if you have a really gigantic range you’d like to generate a list for, say one billion, xrange is the function to use.

This is especially true if you have a really memory sensitive system such as a cell phone that you are working with, as range will use as much memory as it can to create your array of integers, which can result in a Memory Error and crash your program. It’s a memory hungry beast.

Q26. How do you write comments in python?

Ans: Comments in Python start with a # character. However, alternatively at times, commenting is done using docstrings(strings enclosed within triple quotes).

Example:

#Comments in Python start like this
print("Comments in Python start with a #")

Output: Comments in Python start with a #

##3 Q27. What is pickling and unpickling?

Ans: Pickle module accepts any Python object and converts it into a string representation and dumps it into a file by using dump function, this process is called pickling. While the process of retrieving original Python objects from the stored string representation is called unpickling.

Q28. What are the generators in python?

Ans: Functions that return an iterable set of items are called generators.

Q29. How will you capitalize the first letter of string?

Ans: In Python, the capitalize() method capitalizes the first letter of a string. If the string already consists of a capital letter at the beginning, then, it returns the original string.

Q30. How will you convert a string to all lowercase?

Ans: To convert a string to lowercase, lower() function can be used.

Example:

stg='ABCD'
print(stg.lower())

Output: abcd

Q31. How to comment multiple lines in python?

Ans: Multi-line comments appear in more than one line. All the lines to be commented are to be prefixed by a #. You can also a very good shortcut method to comment multiple lines. All you need to do is hold the ctrl key and left click in every place wherever you want to include a # character and type a # just once. This will comment all the lines where you introduced your cursor.

Q32.What are docstrings in Python?

Ans: Docstrings are not actually comments, but, they are documentation strings. These docstrings are within triple quotes. They are not assigned to any variable and therefore, at times, serve the purpose of comments as well.

Example:

"""
Using docstring as a comment.
This code divides 2 numbers
"""
x=8
y=4
z=x/y
print(z)

Output: 2.0

Q33. What is the purpose of is, not and in operators?

Ans: Operators are special functions. They take one or more values and produce a corresponding result.

is: returns true when 2 operands are true (Example: “a” is ‘a’)
not: returns the inverse of the boolean value
in: checks if some element is present in some sequence

Q34. What is the usage of help() and dir() function in Python?

Ans: Help() and dir() both functions are accessible from the Python interpreter and used for viewing a consolidated dump of built-in functions.

• Help() function: The help() function is used to display the documentation string and also facilitates you to see the help related to modules, keywords, attributes, etc.
• Dir() function: The dir() function is used to display the defined symbols.

Q35. Whenever Python exits, why isn’t all the memory de-allocated?

Ans:

• Whenever Python exits, especially those Python modules which are having circular references to other objects or the objects that are referenced from the global namespaces are not always de-allocated or freed.
• It is impossible to de-allocate those portions of memory that are reserved by the C library.
• On exit, because of having its own efficient clean up mechanism, Python would try to de-allocate/destroy every other object.

Q36. What is a dictionary in Python?

Ans: The built-in datatypes in Python is called dictionary. It defines one-to-one relationship between keys and values. Dictionaries contain pair of keys and their corresponding values. Dictionaries are indexed by keys.

Let’s take an example:

The following example contains some keys. Country, Capital & PM. Their corresponding values are India, Delhi and Modi respectively.

dict={'Country':'India','Capital':'Delhi','PM':'Modi'}

print dict[Country]

India

print dict[Capital]

Delhi

print dict[PM]

Modi

Q37. How can the ternary operators be used in python?

Ans: The Ternary operator is the operator that is used to show the conditional statements. This consists of the true or false values with a statement that has to be evaluated for it.

Syntax:

The Ternary operator will be given as:
[on_true] if [expression] else [on_false]x, y = 25, 50big = x if x < y else y

Example:

The expression gets evaluated like if x<y else y, in this case if x<y is true then the value is returned as big=x and if it is incorrect then big=y will be sent as a result.

Q38. What does this mean: *args, **kwargs? And why would we use it?

Ans: We use *args when we aren’t sure how many arguments are going to be passed to a function, or if we want to pass a stored list or tuple of arguments to a function. **kwargs is used when we don’t know how many keyword arguments will be passed to a function, or it can be used to pass the values of a dictionary as keyword arguments. The identifiers args and kwargs are a convention, you could also use *bob and **billy but that would not be wise.

Q39. What does len() do?

Ans: It is used to determine the length of a string, a list, an array, etc.

Example:

stg='ABCD'
len(stg)

Q40. Explain split(), sub(), subn() methods of “re” module in Python.

Ans: To modify the strings, Python’s “re” module is providing 3 methods. They are:

• split() – uses a regex pattern to “split” a given string into a list.
• sub() – finds all substrings where the regex pattern matches and then replace them with a different string
• subn() – it is similar to sub() and also returns the new string along with the no. of replacements.

Q41. What are negative indexes and why are they used?

Ans: The sequences in Python are indexed and it consists of the positive as well as negative numbers. The numbers that are positive uses ‘0’ that is uses as first index and ‘1’ as the second index and the process goes on like that.

The index for the negative number starts from ‘-1’ that represents the last index in the sequence and ‘-2’ as the penultimate index and the sequence carries forward like the positive number.

The negative index is used to remove any new-line spaces from the string and allow the string to except the last character that is given as S[:-1]. The negative index is also used to show the index to represent the string in correct order.

Q42. What are Python packages?

Ans: Python packages are namespaces containing multiple modules.

Q43.How can files be deleted in Python?

Ans: To delete a file in Python, you need to import the OS Module. After that, you need to use the os.remove() function.

Example:

import os
os.remove("xyz.txt")

Q44. What are the built-in types of python?

Ans: Built-in types in Python are as follows –

• Integers
• Floating-point
• Complex numbers
• Strings
• Boolean
• Built-in functions

Q45. What advantages do NumPy arrays offer over (nested) Python lists?

Ans:

• Python’s lists are efficient general-purpose containers. They support (fairly) efficient insertion, deletion, appending, and concatenation, and Python’s list comprehensions make them easy to construct and manipulate.
• They have certain limitations: they don’t support “vectorized” operations like elementwise addition and multiplication, and the fact that they can contain objects of differing types mean that Python must store type information for every element, and must execute type dispatching code when operating on each element.
• NumPy is not just more efficient; it is also more convenient. You get a lot of vector and matrix operations for free, which sometimes allow one to avoid unnecessary work. And they are also efficiently implemented.
• NumPy array is faster and You get a lot built in with NumPy, FFTs, convolutions, fast searching, basic statistics, linear algebra, histograms, etc.

Q46. How to add values to a python array?

Ans: Elements can be added to an array using the append(), extend() and the insert (i,x) functions.

Example:

a=arr.array('d', [1.1 , 2.1 ,3.1] )
a.append(3.4)
print(a)
a.extend([4.5,6.3,6.8])
print(a)
a.insert(2,3.8)
print(a)

Output:
array(‘d’, [1.1, 2.1, 3.1, 3.4])
array(‘d’, [1.1, 2.1, 3.1, 3.4, 4.5, 6.3, 6.8])
array(‘d’, [1.1, 2.1, 3.8, 3.1, 3.4, 4.5, 6.3, 6.8])

Q47. How to remove values to a python array?

Ans: Array elements can be removed using pop() or remove() method. The difference between these two functions is that the former returns the deleted value whereas the latter does not.

Example:

a=arr.array('d', [1.1, 2.2, 3.8, 3.1, 3.7, 1.2, 4.6])
print(a.pop())
print(a.pop(3))
a.remove(1.1)
print(a)

Output:
4.6
3.1
array(‘d’, [2.2, 3.8, 3.7, 1.2])

Q48. Does Python have OOps concepts?

Ans: Python is an object-oriented programming language. This means that any program can be solved in python by creating an object model. However, Python can be treated as procedural as well as structural language.

Q49. What is the difference between deep and shallow copy?

Ans: Shallow copy is used when a new instance type gets created and it keeps the values that are copied in the new instance. Shallow copy is used to copy the reference pointers just like it copies the values. These references point to the original objects and the changes made in any member of the class will also affect the original copy of it. Shallow copy allows faster execution of the program and it depends on the size of the data that is used.

Deep copy is used to store the values that are already copied. Deep copy doesn’t copy the reference pointers to the objects. It makes the reference to an object and the new object that is pointed by some other object gets stored. The changes made in the original copy won’t affect any other copy that uses the object. Deep copy makes execution of the program slower due to making certain copies for each object that is been called.

Q50. How is Multithreading achieved in Python?

Ans:

• Python has a multi-threading package but if you want to multi-thread to speed your code up, then it’s usually not a good idea to use it.
• Python has a construct called the Global Interpreter Lock (GIL). The GIL makes sure that only one of your ‘threads’ can execute at any one time. A thread acquires the GIL, does a little work, then passes the GIL onto the next thread.
• This happens very quickly so to the human eye it may seem like your threads are executing in parallel, but they are really just taking turns using the same CPU core.
• All this GIL passing adds overhead to execution. This means that if you want to make your code run faster then using the threading package often isn’t a good idea.

Q51. What is the process of compilation and linking in python?

Ans: The compiling and linking allows the new extensions to be compiled properly without any error and the linking can be done only when it passes the compiled procedure. If the dynamic loading is used then it depends on the style that is being provided with the system. The python interpreter can be used to provide the dynamic loading of the configuration setup files and will rebuild the interpreter.

The steps that are required in this as:

• Create a file with any name and in any language that is supported by the compiler of your system. For example file.c or file.cpp
• Place this file in the Modules/ directory of the distribution which is getting used.
• Add a line in the file Setup.local that is present in the Modules/ directory.
• Run the file using spam file.o
• After a successful run of this rebuild the interpreter by using the make command on the top-level directory.
• If the file is changed then run rebuildMakefile by using the command as ‘make Makefile’.

Q52. What are Python libraries? Name a few of them.

Python libraries are a collection of Python packages. Some of the majorly used python libraries are – Numpy, Pandas, Matplotlib, Scikit-learn and many more.

Q53. What is split used for?

The split() method is used to separate a given string in Python.

Example:

a="morioh python"
print(a.split())

Output: [‘morioh’, ‘python’]

Q54. How to import modules in python?

Modules can be imported using the import keyword. You can import modules in three ways-

Example:

import array           #importing using the original module name
import array as arr    # importing using an alias name
from array import *    #imports everything present in the array module

OOPS Interview Questions

Q55. Explain Inheritance in Python with an example.

Ans: Inheritance allows One class to gain all the members(say attributes and methods) of another class. Inheritance provides code reusability, makes it easier to create and maintain an application. The class from which we are inheriting is called super-class and the class that is inherited is called a derived / child class.

They are different types of inheritance supported by Python:

• Single Inheritance – where a derived class acquires the members of a single super class.
• Multi-level inheritance – a derived class d1 in inherited from base class base1, and d2 are inherited from base2.
• Hierarchical inheritance – from one base class you can inherit any number of child classes
• Multiple inheritance – a derived class is inherited from more than one base class.

Q56. How are classes created in Python?

Ans: Class in Python is created using the class keyword.

Example:

class Employee:
def __init__(self, name):
self.name = name
E1=Employee("abc")
print(E1.name)

Output: abc

Q57. What is monkey patching in Python?

Ans: In Python, the term monkey patch only refers to dynamic modifications of a class or module at run-time.

Consider the below example:

# m.py
class MyClass:
def f(self):
print "f()"

We can then run the monkey-patch testing like this:

import m
def monkey_f(self):
print "monkey_f()"
 
m.MyClass.f = monkey_f
obj = m.MyClass()
obj.f()

The output will be as below:
monkey_f()

As we can see, we did make some changes in the behavior of f() in MyClass using the function we defined, monkey_f(), outside of the module m.

Q58. Does python support multiple inheritance?

Ans: Multiple inheritance means that a class can be derived from more than one parent classes. Python does support multiple inheritance, unlike Java.

Q59. What is Polymorphism in Python?

Ans: Polymorphism means the ability to take multiple forms. So, for instance, if the parent class has a method named ABC then the child class also can have a method with the same name ABC having its own parameters and variables. Python allows polymorphism.

Q60. Define encapsulation in Python?

Ans: Encapsulation means binding the code and the data together. A Python class in an example of encapsulation.

Q61. How do you do data abstraction in Python?

Ans: Data Abstraction is providing only the required details and hiding the implementation from the world. It can be achieved in Python by using interfaces and abstract classes.

Q62.Does python make use of access specifiers?

Ans: Python does not deprive access to an instance variable or function. Python lays down the concept of prefixing the name of the variable, function or method with a single or double underscore to imitate the behavior of protected and private access specifiers.

Q63. How to create an empty class in Python?

Ans: An empty class is a class that does not have any code defined within its block. It can be created using the pass keyword. However, you can create objects of this class outside the class itself. IN PYTHON THE PASS command does nothing when its executed. it’s a null statement.

For example-

class a:
    pass
obj=a()
obj.name="xyz"
print("Name = ",obj.name)

Output:
Name = xyz

Q64. What does an object() do?

Ans: It returns a featureless object that is a base for all classes. Also, it does not take any parameters.

Basic Python Programs

Q65. Write a program in Python to execute the Bubble sort algorithm.

def bs(a):             # a = name of list
    b=len(a)-1         # minus 1 because we always compare 2 adjacent values
                             
    for x in range(b):
        for y in range(b-x):
            if a[y]>a[y+1]:
                a[y],a[y+1]=a[y+1],a[y]
    return a
a=[32,5,3,6,7,54,87]
bs(a)

Output: [3, 5, 6, 7, 32, 54, 87]

Q66. Write a program in Python to produce Star triangle.

def pyfunc(r):
    for x in range(r):
        print(' '*(r-x-1)+'*'*(2*x+1))    
pyfunc(9)

Output:

    *
   ***
  *****
 *******
*********

---

---

---

---

Q67. Write a program to produce Fibonacci series in Python.

# Enter number of terms needed                   #0,1,1,2,3,5....
a=int(input("Enter the terms"))
f=0                                         #first element of series
s=1                                         #second element of series
if a<=0:
    print("The requested series is
",f)
else:
    print(f,s,end=" ")
    for x in range(2,a):
        next=f+s                           
        print(next,end=" ")
        f=s
        s=next</pre>

Output: Enter the terms 5 0 1 1 2 3

Q68. Write a program in Python to check if a number is prime.

a=int(input("enter number"))     
if a>1:
    for x in range(2,a):
        if(a%x)==0:
            print("not prime")
            break
    else:
        print("Prime")
else:
    print("not prime")

Output:
enter number 3
Prime

Q69. Write a program in Python to check if a sequence is a Palindrome.

a=input("enter sequence")
b=a[::-1]
if a==b:
    print("palindrome")
else:
    print("Not a Palindrome")

Output:
enter sequence 323 palindrome

Q70. Write a one-liner that will count the number of capital letters in a file. Your code should work even if the file is too big to fit in memory.

Ans: Let us first write a multiple line solution and then convert it to one-liner code.

with open(SOME_LARGE_FILE) as fh:
count = 0
text = fh.read()
for character in text:
    if character.isupper():
count += 1

We will now try to transform this into a single line.

count sum(1 for line in fh for character in line if character.isupper())

Q71. Write a sorting algorithm for a numerical dataset in Python.

Ans: The following code can be used to sort a list in Python:

list = ["1", "4", "0", "6", "9"]
list = [int(i) for i in list]
list.sort()
print (list)

Q72. Looking at the below code, write down the final values of A0, A1, …An.

A0 = dict(zip(('a','b','c','d','e'),(1,2,3,4,5)))
A1 = range(10)A2 = sorted([i for i in A1 if i in A0])
A3 = sorted([A0[s] for s in A0])
A4 = [i for i in A1 if i in A3]
A5 = {i:i*i for i in A1}
A6 = [[i,i*i] for i in A1]
print(A0,A1,A2,A3,A4,A5,A6)

Ans: The following will be the final outputs of A0, A1, … A6

A0 = {‘a’: 1, ‘c’: 3, ‘b’: 2, ‘e’: 5, ‘d’: 4} # the order may vary
A1 = range(0, 10)
A2 = []
A3 = [1, 2, 3, 4, 5]
A4 = [1, 2, 3, 4, 5]
A5 = {0: 0, 1: 1, 2: 4, 3: 9, 4: 16, 5: 25, 6: 36, 7: 49, 8: 64, 9: 81}
A6 = [[0, 0], [1, 1], [2, 4], [3, 9], [4, 16], [5, 25], [6, 36], [7, 49], [8, 64], [9, 81]]

Python Libraries Interview Questions

Q73. Explain what Flask is and its benefits?

Ans: Flask is a web microframework for Python based on “Werkzeug, Jinja2 and good intentions” BSD license. Werkzeug and Jinja2 are two of its dependencies. This means it will have little to no dependencies on external libraries. It makes the framework light while there is a little dependency to update and fewer security bugs.

A session basically allows you to remember information from one request to another. In a flask, a session uses a signed cookie so the user can look at the session contents and modify. The user can modify the session if only it has the secret key Flask.secret_key.

Q74. Is Django better than Flask?

Ans: Django and Flask map the URL’s or addresses typed in the web browsers to functions in Python.

Flask is much simpler compared to Django but, Flask does not do a lot for you meaning you will need to specify the details, whereas Django does a lot for you wherein you would not need to do much work. Django consists of prewritten code, which the user will need to analyze whereas Flask gives the users to create their own code, therefore, making it simpler to understand the code. Technically both are equally good and both contain their own pros and cons.

Q75. Mention the differences between Django, Pyramid and Flask.

Ans:

• Flask is a “microframework” primarily build for a small application with simpler requirements. In flask, you have to use external libraries. Flask is ready to use.
• Pyramid is built for larger applications. It provides flexibility and lets the developer use the right tools for their project. The developer can choose the database, URL structure, templating style and more. Pyramid is heavy configurable.
• Django can also be used for larger applications just like Pyramid. It includes an ORM.

Q76. Discuss Django architecture.

Ans: Django MVT Pattern:

The developer provides the Model, the view and the template then just maps it to a URL and Django does the magic to serve it to the user.

Q77. Explain how you can set up the Database in Django.

Ans: You can use the command edit mysite/setting.py, it is a normal python module with module level representing Django settings.

Django uses SQLite by default; it is easy for Django users as such it won’t require any other type of installation. In the case your database choice is different that you have to the following keys in the DATABASE ‘default’ item to match your database connection settings.

• Engines: you can change the database by using ‘django.db.backends.sqlite3’ , ‘django.db.backeneds.mysql’, ‘django.db.backends.postgresql_psycopg2’, ‘django.db.backends.oracle’ and so on
• Name: The name of your database. In the case if you are using SQLite as your database, in that case, database will be a file on your computer, Name should be a full absolute path, including the file name of that file.
• If you are not choosing SQLite as your database then settings like Password, Host, User, etc. must be added.

Django uses SQLite as a default database, it stores data as a single file in the filesystem. If you do have a database server—PostgreSQL, MySQL, Oracle, MSSQL—and want to use it rather than SQLite, then use your database’s administration tools to create a new database for your Django project. Either way, with your (empty) database in place, all that remains is to tell Django how to use it. This is where your project’s settings.py file comes in.

We will add the following lines of code to the setting.py file:

DATABASES = {
     'default': {
          'ENGINE' : 'django.db.backends.sqlite3',
          'NAME' : os.path.join(BASE_DIR, 'db.sqlite3'),
     }
}

Q78. Give an example how you can write a VIEW in Django?

Ans: This is how we can use write a view in Django:

from django.http import HttpResponse
import datetime
 
def Current_datetime(request):
     now = datetime.datetime.now()
     html = "<html><body>It is now %s</body></html> % now
     return HttpResponse(html)

Returns the current date and time, as an HTML document

Q79. Mention what the Django templates consist of.

Ans: The template is a simple text file. It can create any text-based format like XML, CSV, HTML, etc. A template contains variables that get replaced with values when the template is evaluated and tags (% tag %) that control the logic of the template.

Q80. Explain the use of session in Django framework?

Ans: Django provides a session that lets you store and retrieve data on a per-site-visitor basis. Django abstracts the process of sending and receiving cookies, by placing a session ID cookie on the client side, and storing all the related data on the server side.

So the data itself is not stored client side. This is nice from a security perspective.

Q81. List out the inheritance styles in Django.

Ans: In Django, there are three possible inheritance styles:

• Abstract Base Classes: This style is used when you only want parent’s class to hold information that you don’t want to type out for each child model.
• Multi-table Inheritance: This style is used If you are sub-classing an existing model and need each model to have its own database table.
• Proxy models: You can use this model, If you only want to modify the Python level behavior of the model, without changing the model’s fields.

Web Scraping – Python Interview Questions

Q82. How To Save An Image Locally Using Python Whose URL Address I Already Know?

Ans: We will use the following code to save an image locally from an URL address

import urllib.request
urllib.request.urlretrieve("URL", "local-filename.jpg")

Q83. How can you Get the Google cache age of any URL or web page?

Ans: Use the following URL format:

http://webcache.googleusercontent.com/search?q=cache:URLGOESHERE

Be sure to replace “URLGOESHERE” with the proper web address of the page or site whose cache you want to retrieve and see the time for. For example, to check the Google Webcache age of edureka.co you’d use the following URL:

http://webcache.googleusercontent.com/search?q=cache:edureka.co

Q84. You are required to scrap data from IMDb top 250 movies page. It should only have fields movie name, year, and rating.

Ans: We will use the following lines of code:

from bs4 import BeautifulSoup
 
import requests
import sys
 
url = '<a href="http://www.imdb.com/chart/top">http://www.imdb.com/chart/top</a>'
response = requests.get(url)
soup = BeautifulSoup(response.text)
tr = soup.findChildren("tr")
tr = iter(tr)
next(tr)
 
for movie in tr:
title = movie.find('td', {'class': 'titleColumn'} ).find('a').contents[0]
year = movie.find('td', {'class': 'titleColumn'} ).find('span', {'class': 'secondaryInfo'}).contents[0]
rating = movie.find('td', {'class': 'ratingColumn imdbRating'} ).find('strong').contents[0]
row = title + ' - ' + year + ' ' + ' ' + rating
 
print(row)

The above code will help scrap data from IMDb’s top 250 list

Data Analysis – Python Interview Questions

Q85. What is map function in Python?

Ans: map function executes the function given as the first argument on all the elements of the iterable given as the second argument. If the function given takes in more than 1 arguments, then many iterables are given. #Follow the link to know more similar functions.

Q86. Is python numpy better than lists?

Ans: We use python numpy array instead of a list because of the below three reasons:

• Less Memory
• Fast
• Convenient

For more information on these parameters, you can refer to this section – Numpy Vs List.

Q87. How to get indices of N maximum values in a NumPy array?

Ans: We can get the indices of N maximum values in a NumPy array using the below code:

import numpy as np
arr = np.array([1, 3, 2, 4, 5])
print(arr.argsort()[-3:][::-1])

Output
[ 4 3 1 ]

Q88. How do you calculate percentiles with Python/ NumPy?

Ans: We can calculate percentiles with the following code

import numpy as np
a = np.array([1,2,3,4,5])
p = np.percentile(a, 50) #Returns 50th percentile, e.g. median
print(p)

Output
3

Q89. What is the difference between NumPy and SciPy?

Ans:

• In an ideal world, NumPy would contain nothing but the array data type and the most basic operations: indexing, sorting, reshaping, basic elementwise functions, et cetera.
• All numerical code would reside in SciPy. However, one of NumPy’s important goals is compatibility, so NumPy tries to retain all features supported by either of its predecessors.
• Thus NumPy contains some linear algebra functions, even though these more properly belong in SciPy. In any case, SciPy contains more fully-featured versions of the linear algebra modules, as well as many other numerical algorithms.
• If you are doing scientific computing with python, you should probably install both NumPy and SciPy. Most new features belong in SciPy rather than NumPy.

Q90. How do you make 3D plots/visualizations using NumPy/SciPy?

Ans: Like 2D plotting, 3D graphics is beyond the scope of NumPy and SciPy, but just as in the 2D case, packages exist that integrate with NumPy. Matplotlib provides basic 3D plotting in the mplot3d subpackage, whereas Mayavi provides a wide range of high-quality 3D visualization features, utilizing the powerful VTK engine.

Multiple Choice Questions (MCQ)

Q91. Which of the following statements create a dictionary? (Multiple Correct Answers Possible)

a) d = {}
b) d = {“john”:40, “peter”:45}
c) d = {40:”john”, 45:”peter”}
d) d = (40:”john”, 45:”50”)

Answer: b, c & d.

Dictionaries are created by specifying keys and values.

Q92. Which one of these is floor division?

a) /
b) //
c) %
d) None of the mentioned

Answer: b) //

When both of the operands are integer then python chops out the fraction part and gives you the round off value, to get the accurate answer use floor division. For ex, 5/2 = 2.5 but both of the operands are integer so answer of this expression in python is 2. To get the 2.5 as the answer, use floor division using //. So, 5//2 = 2.5

Q93. What is the maximum possible length of an identifier?

a) 31 characters
b) 63 characters
c) 79 characters
d) None of the above

Answer: d) None of the above

Identifiers can be of any length.

Q94. Why are local variable names beginning with an underscore discouraged?

a) they are used to indicate a private variables of a class
b) they confuse the interpreter
c) they are used to indicate global variables
d) they slow down execution

Answer: a) they are used to indicate a private variable of a class

As Python has no concept of private variables, leading underscores are used to indicate variables that must not be accessed from outside the class.

Q95. Which of the following is an invalid statement?

a) abc = 1,000,000
b) a b c = 1000 2000 3000
c) a,b,c = 1000, 2000, 3000
d) a_b_c = 1,000,000

Answer: b) a b c = 1000 2000 3000

Spaces are not allowed in variable names.

Q96. What is the output of the following?

try:
    if '1' != 1:
        raise "someError"
    else:
        print("someError has not occured")
except "someError":
    print ("someError has occured")

a) someError has occured
b) someError has not occured
c) invalid code
d) none of the above

Answer: c) invalid code

A new exception class must inherit from a BaseException. There is no such inheritance here.

Q97. Suppose list1 is [2, 33, 222, 14, 25], What is list1[-1] ?

a) Error
b) None
c) 25
d) 2

Answer: c) 25

The index -1 corresponds to the last index in the list.

Q98. To open a file c:scores.txt for writing, we use

a) outfile = open(“c:scores.txt”, “r”)
b) outfile = open(“c:scores.txt”, “w”)
c) outfile = open(file = “c:scores.txt”, “r”)
d) outfile = open(file = “c:scores.txt”, “o”)

Answer: b) The location contains double slashes ( ) and w is used to indicate that file is being written to.

Q99. What is the output of the following?

f = None
 
for i in range (5):
    with open("data.txt", "w") as f:
        if i > 2:
            break
 
print f.closed

a) True
b) False
c) None
d) Error

Answer: a) True

The WITH statement when used with open file guarantees that the file object is closed when the with block exits.

Q100. When will the else part of try-except-else be executed?

a) always
b) when an exception occurs
c) when no exception occurs
d) when an exception occurs into except block

Answer: c) when no exception occurs

The else part is executed when no exception occurs.

I hope this set of Python Interview Questions will help you in preparing for your interviews. All the best!

Originally published at https://www.edureka.co

#python #interview #interview-questions

Lambda, Map, Filter functions in python

Welcome to my Blog, In this article, we will learn python lambda function, Map function, and filter function.

Lambda function in python: Lambda is a one line anonymous function and lambda takes any number of arguments but can only have one expression and python lambda syntax is

Syntax: x = lambda arguments : expression

Now i will show you some python lambda function examples:

#python #anonymous function python #filter function in python #lambda #lambda python 3 #map python #python filter #python filter lambda #python lambda #python lambda examples #python map

Top 20 Most Useful Python Modules or Packages

 March 25, 2021  Deepak@321  0 Comments

Welcome to my blog, In this article, we will learn the top 20 most useful python modules or packages and these modules every Python developer should know.

Hello everybody and welcome back so in this article I’m going to be sharing with you 20 Python modules you need to know. Now I’ve split these python modules into four different categories to make little bit easier for us and the categories are:

1. Web Development
2. Data Science
3. Machine Learning
4. AI and graphical user interfaces.

Near the end of the article, I also share my personal favorite Python module so make sure you stay tuned to see what that is also make sure to share with me in the comments down below your favorite Python module.

#python #packages or libraries #python 20 modules #python 20 most usefull modules #python intersting modules #top 20 python libraries #top 20 python modules #top 20 python packages