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Python 字典方法 – Python 中的字典
在 Python 中，字典是核心数据结构之一。它是由逗号分隔并用花括号括起来的键值对序列。
如果您熟悉 JavaScript，那么 Python 字典就像 JavaScript 对象。
Python 提供了 10 多种使用字典的方法。
在本文中，我将向您展示如何在 Python 中创建字典并使用这些方法使用它。
如何在 Python 中创建字典
要创建字典，您需要打开一个花括号并将数据放在一个以逗号分隔的键值对中。
字典的基本语法如下所示：
demo_dict = {
"key1": "value1",
"key2": "value2",
"key3": "value3"
}
请注意，值可以是任何数据类型并且可以重复，但键不能重复。如果键重复，您将收到无效的语法错误。
使用 Python 字典的方法
我将使用下面的字典向您展示字典方法的工作原理：
first_dict = {
"name": "freeCodeCamp",
"founder": "Quincy Larson",
"type": "charity",
"age": 8,
"price": "free",
"work-style": "remote",
}
如何使用get()字典法
get 方法返回指定键的值。
founder在下面的代码中，我可以通过在方法中传递密钥来获取 freeCodeCamp 的创始人get()：
first_dict = {
"name": "freeCodeCamp",
"founder": "Quincy Larson",
"type": "charity",
"age": 8,
"price": "free",
"work-style": "remote",
}
founder = first_dict.get("founder")
print(founder)
# Output: Quincy Larson
如何使用items()字典法
该items()方法以列表的形式返回字典的所有条目。列表中有一个表示每个项目的元组。
first_dict = {
"name": "freeCodeCamp",
"founder": "Quincy Larson",
"type": "charity",
"age": 8,
"price": "free",
"work-style": "remote",
}
items = first_dict.items()
print(items)
# Output: dict_items([('name', 'freeCodeCamp'), ('founder', 'Quincy Larson'), ('type', 'charity'), ('age', 8), ('price', 'free'), ('work-style', 'remote')])
如何使用keys()字典法
返回字典中的keys()所有键。它返回元组中的键——另一种 Python 数据结构。
first_dict = {
"name": "freeCodeCamp",
"founder": "Quincy Larson",
"type": "charity",
"age": 8,
"price": "free",
"work-style": "remote",
}
dict_keys = first_dict.keys()
print(dict_keys)
# Output: dict_keys(['name', 'founder', 'type', 'age', 'price', 'work-style'])
如何使用values()字典法
values 方法访问字典中的所有值。与该keys()方法一样，它返回元组中的值。
first_dict = {
"name": "freeCodeCamp",
"founder": "Quincy Larson",
"type": "charity",
"age": 8,
"price": "free",
"work-style": "remote",
}
dict_values = first_dict.values()
print(dict_values)
# Output: dict_values(['freeCodeCamp', 'Quincy Larson', 'charity', 8, 'free', 'remote'])
如何使用pop()字典法
该pop()方法从字典中删除一个键值对。要使其工作，您需要在其括号内指定键。
first_dict = {
"name": "freeCodeCamp",
"founder": "Quincy Larson",
"type": "charity",
"age": 8,
"price": "free",
"work-style": "remote",
}
first_dict.pop("work-style")
print(first_dict)
# Output: {'name': 'freeCodeCamp', 'founder': 'Quincy Larson', 'type': 'charity', 'age': 8, 'price': 'free'}
您可以看到work-style键及其值已从字典中删除。
如何使用popitem()字典法
该popitem()方法与该pop()方法一样工作。不同之处在于它删除了字典中的最后一项。
first_dict = {
"name": "freeCodeCamp",
"founder": "Quincy Larson",
"type": "charity",
"age": 8,
"price": "free",
"work-style": "remote",
}
first_dict.popitem()
print(first_dict)
# Output: {'name': 'freeCodeCamp', 'founder': 'Quincy Larson', 'type': 'charity', 'age': 8, 'price': 'free'}
您可以看到最后一个键值对（“work-style”：“remote”）已从字典中删除。
如何使用update()字典法
该update()方法将一个项目添加到字典中。您必须在其大括号内指定键和值，并用花括号将其括起来。
first_dict = {
"name": "freeCodeCamp",
"founder": "Quincy Larson",
"type": "charity",
"age": 8,
"price": "free",
"work-style": "remote",
}
first_dict.update({"Editor": "Abbey Rennemeyer"})
print(first_dict)
# Output: {'name': 'freeCodeCamp', 'founder': 'Quincy Larson', 'type': 'charity', 'age': 8, 'price': 'free', 'work-style': 'remote', 'Editor': 'Abbey Rennemeyer'}
新条目已添加到字典中。
如何使用copy()字典法
该copy()方法正如其名称所暗示的那样 - 它将字典复制到指定的变量中。
first_dict = {
"name": "freeCodeCamp",
"founder": "Quincy Larson",
"type": "charity",
"age": 8,
"price": "free",
"work-style": "remote",
}
second_dict = first_dict.copy()
print(second_dict)
# Output: {'name': 'freeCodeCamp', 'founder': 'Quincy Larson', 'type': 'charity', 'age': 8, 'price': 'free', 'work-style': 'remote'}
如何使用clear()字典法
clear 方法删除字典中的所有条目。
first_dict = {
"name": "freeCodeCamp",
"founder": "Quincy Larson",
"type": "charity",
"age": 8,
"price": "free",
"work-style": "remote",
}
first_dict.clear()
print(first_dict)
# Output: {}
结论
在本文中，您学习了如何创建 Python 字典以及如何使用 Python 提供的内置方法来使用它。
如果您觉得这篇文章有帮助，请不要犹豫，与朋友和家人分享。
继续编码:)
来源：https ://www.freecodecamp.org/news/python-dictionary-methods-dictionaries-in-python/
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1626775355
Why use Python for Software Development
No programming language is pretty much as diverse as Python. It enables building cutting edge applications effortlessly. Developers are as yet investigating the full capability of end-to-end Python development services in various areas.
By areas, we mean FinTech, HealthTech, InsureTech, Cybersecurity, and that's just the beginning. These are New Economy areas, and Python has the ability to serve every one of them. The vast majority of them require massive computational abilities. Python's code is dynamic and powerful - equipped for taking care of the heavy traffic and substantial algorithmic capacities.
Programming advancement is multidimensional today. Endeavor programming requires an intelligent application with AI and ML capacities. Shopper based applications require information examination to convey a superior client experience. Netflix, Trello, and Amazon are genuine instances of such applications. Python assists with building them effortlessly.
5 Reasons to Utilize Python for Programming Web Apps
Python can do such numerous things that developers can't discover enough reasons to admire it. Python application development isn't restricted to web and enterprise applications. It is exceptionally adaptable and superb for a wide range of uses.
Robust frameworks
Python is known for its tools and frameworks. There's a structure for everything. Django is helpful for building web applications, venture applications, logical applications, and mathematical processing. Flask is another web improvement framework with no conditions.
Web2Py, CherryPy, and Falcon offer incredible capabilities to customize Python development services. A large portion of them are open-source frameworks that allow quick turn of events.
Simple to read and compose
Python has an improved sentence structure - one that is like the English language. New engineers for Python can undoubtedly understand where they stand in the development process. The simplicity of composing allows quick application building.
The motivation behind building Python, as said by its maker Guido Van Rossum, was to empower even beginner engineers to comprehend the programming language. The simple coding likewise permits developers to roll out speedy improvements without getting confused by pointless subtleties.
Utilized by the best
Alright - Python isn't simply one more programming language. It should have something, which is the reason the business giants use it. Furthermore, that too for different purposes. Developers at Google use Python to assemble framework organization systems, parallel information pusher, code audit, testing and QA, and substantially more. Netflix utilizes Python web development services for its recommendation algorithm and media player.
Massive community support
Python has a steadily developing community that offers enormous help. From amateurs to specialists, there's everybody. There are a lot of instructional exercises, documentation, and guides accessible for Python web development solutions.
Today, numerous universities start with Python, adding to the quantity of individuals in the community. Frequently, Python designers team up on various tasks and help each other with algorithmic, utilitarian, and application critical thinking.
Progressive applications
Python is the greatest supporter of data science, Machine Learning, and Artificial Intelligence at any enterprise software development company. Its utilization cases in cutting edge applications are the most compelling motivation for its prosperity. Python is the second most well known tool after R for data analytics.
The simplicity of getting sorted out, overseeing, and visualizing information through unique libraries makes it ideal for data based applications. TensorFlow for neural networks and OpenCV for computer vision are two of Python's most well known use cases for Machine learning applications.
Summary
Thinking about the advances in programming and innovation, Python is a YES for an assorted scope of utilizations. Game development, web application development services, GUI advancement, ML and AI improvement, Enterprise and customer applications - every one of them uses Python to its full potential.
The disadvantages of Python web improvement arrangements are regularly disregarded by developers and organizations because of the advantages it gives. They focus on quality over speed and performance over blunders. That is the reason it's a good idea to utilize Python for building the applications of the future.
#python development services #python development company #python app development #python development #python in web development #python software development
1602968400
Python Tricks Every Developer Should Know
Python is awesome, it’s one of the easiest languages with simple and intuitive syntax but wait, have you ever thought that there might ways to write your python code simpler?
In this tutorial, you’re going to learn a variety of Python tricks that you can use to write your Python code in a more readable and efficient way like a pro.
Let’s get started
Swapping value in Python
Instead of creating a temporary variable to hold the value of the one while swapping, you can do this instead
>>> FirstName = "kalebu"
>>> LastName = "Jordan"
>>> FirstName, LastName = LastName, FirstName
>>> print(FirstName, LastName)
('Jordan', 'kalebu')
#python #python-programming #python3 #python-tutorials #learn-python #python-tips #python-skills #python-development
1602666000
How to Remove all Duplicate Files on your Drive via Python
Today you’re going to learn how to use Python programming in a way that can ultimately save a lot of space on your drive by removing all the duplicates.
Intro
In many situations you may find yourself having duplicates files on your disk and but when it comes to tracking and checking them manually it can tedious.
Heres a solution
Instead of tracking throughout your disk to see if there is a duplicate, you can automate the process using coding, by writing a program to recursively track through the disk and remove all the found duplicates and that’s what this article is about.
But How do we do it?
If we were to read the whole file and then compare it to the rest of the files recursively through the given directory it will take a very long time, then how do we do it?
The answer is hashing, with hashing can generate a given string of letters and numbers which act as the identity of a given file and if we find any other file with the same identity we gonna delete it.
There’s a variety of hashing algorithms out there such as
- md5
- sha1
- sha224, sha256, sha384 and sha512
#python-programming #python-tutorials #learn-python #python-project #python3 #python #python-skills #python-tips
1597751700
How To Compare Tesla and Ford Company By Using Magic Methods in Python
Magic Methods are the special methods which gives us the ability to access built in syntactical features such as ‘<’, ‘>’, ‘==’, ‘+’ etc…
You must have worked with such methods without knowing them to be as magic methods. Magic methods can be identified with their names which start with __ and ends with __ like init, call, str etc. These methods are also called Dunder Methods, because of their name starting and ending with Double Underscore (Dunder).
Now there are a number of such special methods, which you might have come across too, in Python. We will just be taking an example of a few of them to understand how they work and how we can use them.
1. init
class AnyClass:
def __init__():
print("Init called on its own")
obj = AnyClass()
The first example is _init, _and as the name suggests, it is used for initializing objects. Init method is called on its own, ie. whenever an object is created for the class, the init method is called on its own.
The output of the above code will be given below. Note how we did not call the init method and it got invoked as we created an object for class AnyClass.
Init called on its own
2. add
Let’s move to some other example, add gives us the ability to access the built in syntax feature of the character +. Let’s see how,
class AnyClass:
def __init__(self, var):
self.some_var = var
def __add__(self, other_obj):
print("Calling the add method")
return self.some_var + other_obj.some_var
obj1 = AnyClass(5)
obj2 = AnyClass(6)
obj1 + obj2
#python3 #python #python-programming #python-web-development #python-tutorials #python-top-story #python-tips #learn-python
1593156510
Basic Data Types in Python | Python Web Development For Beginners
At the end of 2019, Python is one of the fastest-growing programming languages. More than 10% of developers have opted for Python development.
In the programming world, Data types play an important role. Each Variable is stored in different data types and responsible for various functions. Python had two different objects, and They are mutable and immutable objects.
Table of Contents hide
III Built-in data types in Python
Mutable objects
The Size and declared value and its sequence of the object can able to be modified called mutable objects.
Mutable Data Types are list, dict, set, byte array
Immutable objects
The Size and declared value and its sequence of the object can able to be modified.
Immutable data types are int, float, complex, String, tuples, bytes, and frozen sets.
id() and type() is used to know the Identity and data type of the object
a**=25+**85j
type**(a)**
output**:<class’complex’>**
b**={1:10,2:“Pinky”****}**
id**(b)**
output**:**238989244168
Built-in data types in Python
a**=str(“Hello python world”)****#str**
b**=int(18)****#int**
c**=float(20482.5)****#float**
d**=complex(5+85j)****#complex**
e**=list((“python”,“fast”,“growing”,“in”,2018))****#list**
f**=tuple((“python”,“easy”,“learning”))****#tuple**
g**=range(10)****#range**
h**=dict(name=“Vidu”,age=36)****#dict**
i**=set((“python”,“fast”,“growing”,“in”,2018))****#set**
j**=frozenset((“python”,“fast”,“growing”,“in”,2018))****#frozenset**
k**=bool(18)****#bool**
l**=bytes(8)****#bytes**
m**=bytearray(8)****#bytearray**
n**=memoryview(bytes(18))****#memoryview**
Numbers (int,Float,Complex)
Numbers are stored in numeric Types. when a number is assigned to a variable, Python creates Number objects.
#signed interger
age**=**18
print**(age)**
Output**:**18
Python supports 3 types of numeric data.
int (signed integers like 20, 2, 225, etc.)
float (float is used to store floating-point numbers like 9.8, 3.1444, 89.52, etc.)
complex (complex numbers like 8.94j, 4.0 + 7.3j, etc.)
A complex number contains an ordered pair, i.e., a + ib where a and b denote the real and imaginary parts respectively).
String
The string can be represented as the sequence of characters in the quotation marks. In python, to define strings we can use single, double, or triple quotes.
# String Handling
‘Hello Python’
#single (') Quoted String
“Hello Python”
# Double (") Quoted String
“”“Hello Python”“”
‘’‘Hello Python’‘’
# triple (‘’') (“”") Quoted String
In python, string handling is a straightforward task, and python provides various built-in functions and operators for representing strings.
The operator “+” is used to concatenate strings and “*” is used to repeat the string.
“Hello”+“python”
output**:****‘Hello python’**
"python "*****2
'Output : Python python ’
#python web development #data types in python #list of all python data types #python data types #python datatypes #python types #python variable type