Using **pyenv** to Install Multiple Python Versions for Project

Managing multiple versions of Python on a Linux system is not an easy task, especially for beginners. Sometimes it even gets worse when you want to develop and run multiple projects with different Python versions on the same server. However, this shouldn’t be the case if you employ pyenv.

What is Pyenv?

Pyenv is a simple, powerful and cross-platform tool for managing multiple Python versions on Linux systems, that used for.

• Switching the global Python version on a per-user basis.
• setting the local Python version on per-project basis.
• Managing of virtual environments created by anaconda or virtualenv.
• Overriding the Python version with an environment variable.
• Searching commands from multiple versions of Python and more.

How Does pyenv Work?

Usually, a single default version of Python is used to run all your applications, unless you explicitly specify the version you want to use within the application. But pyenv implements a simple concept of using shims (lightweight executables) to pass your command to the correct Python version you want to use, when you have multiple versions installed.

These shims are inserted by pyenv in a directories in front of your PATH. So when you run a Python command, it is intercepted by the appropriate shim and passed to pyenv, which then establishes the Python version that has been specified by your application, and passes your commands along to the rightful Python installation. This is an overview of how pyenv operates.

In this article, we will show how to install the latest version of pyenv in Linux. We will also demonstrate the first three uses case listed above.

How to Install Pyenv in Linux

1. First install all the required packages for installing different Python versions from sources using following command on your respective Linux distribution.

------------ On Debian/Ubuntu/Linux Mint ------------ 
$ sudo apt install curl git-core gcc make zlib1g-dev libbz2-dev libreadline-dev libsqlite3-dev libssl-dev

------------ On CentOS/RHEL ------------
# yum -y install epel-release
# yum install git gcc zlib-devel bzip2-devel readline-devel sqlite-devel openssl-devel

------------ On Fedora 22+ ------------
# yum install git gcc zlib-devel bzip2-devel readline-devel sqlite-devel openssl-devel

2. Next, grab the the latest pyenv source tree from its Github repository and install it in $HOME/.pyenv path using following command.

$ git clone https://github.com/pyenv/pyenv.git $HOME/.pyenv

3. Now you need to set the environment variable PYENV_ROOT to point to the path where you installed pyenv and export it. Then add $PYENV_ROOT/bin to your PATH to run pyenv command-line utility like any other system commands.

You also need to enable shims as well as autocompletion by adding the pyenv init to your shell. Do all these things in your $HOME/.bashrc bash startup file, as shown.

$ vim $HOME/.bashrc 

Copy and paste the following lines at the end of this file.

## pyenv configs
export PYENV_ROOT="$HOME/.pyenv"
export PATH="$PYENV_ROOT/bin:$PATH"

if command -v pyenv 1>/dev/null 2>&1; then
  eval "$(pyenv init -)"
fi

4. Once you have made the above changes, you can either source $HOME/.bashrc file or restart the shell as shown.

$ source $HOME/.bashrc
OR
$ exec "$SHELL"

How to Install Multiple Python Versions in Linux

5. At this point, you should be ready to start using pyenv. Before you install any Python version, you can view all available versions with this command.

$ pyenv install -l

List Multiple Python Versions

6. You can now install multiple Python version via pyenv, for example.

$ pyenv install 3.6.4
$ pyenv install 3.6.5

Install Multiple Python Versions

7. To list all Python versions available to pyenv, run the following command. This will only show versions installed via pyenv itself.

$ pyenv versions

List Installed Python Versions

8. You can check the global Python version with the following command, by this time, the default version should be the one set by the system, not pyenv.

$ pyenv global

You can set the global python version using the pyenv command.

$ pyenv global 3.6.5
$ pyenv global

Set Global Python Version

9. You can now set the local Python version on per-project basis, for instance, if you have a project located in $HOME/python_projects/test, you can set the Python version of it using following command.

$ cd python_projects/test
$ pyenv local 3.6.5
$ pyenv version		#view local python version for a specific project 
OR
$ pyenv versions

Set Python Version for Project

10. Pyenv manages virtual environments via the pyenv-virtualenv plugin which automates management of virtualenvs and conda environments for Python on Linux and other UNIX-like systems.

You can start by installing this plugin using following commands.

$ git clone https://github.com/yyuu/pyenv-virtualenv.git   $HOME/.pyenv/plugins/pyenv-virtualenv
$ source $HOME/.bashrc

11. Now we will create a test virtual environment called venv_project1 under a project called project1 as follows.

$ cd python_projects
$ mkdir project1
$ cd project1
$ pyenv virtualenv 3.6.5 venv_project1

Create a Virtual Environment

12. Now when you list all Python versions, your virtual environments as well as their local python versions should be listed also, as shown in the screenshot.

$ pyenv versions

List Python Versions

13. To activate a virtualenv, for example venv_project1, type following command.

$ pyenv activate venv_project1

Note: You may get the message below while using the latest version of pyenv-virtualenv plugin for the first time.

pyenv-virtualenv: prompt changing will be removed from future release. configure `export PYENV_VIRTUALENV_DISABLE_PROMPT=1' to simulate the behavior.

Add the line export PYENV_VIRTUALENV_DISABLE_PROMPT=1 in your $HOME/.bashrc file, where you added other pyenv configs, and source the file to simulate the behavior being emphasized.

14. To deactivate the activated virtualenv, run this command.

$ pyenv deactivate

For more information, you can list all pyenv commands using following command.

$ pyenv commands

For more information, go to the pyenv Github repository: https://github.com/pyenv/pyenv

Using pyenv is really that simple. In this guide, we showed how to install it, as well as demonstrated some of its use cases for managing multiple python versions on a Linux system. Use the feedback form below to ask any questions or share your thoughts about this tool.

Thank you for reading!

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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.

…

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42 Exciting Python Project Ideas & Topics for Beginners [2021]

Python Project Ideas

Python is one of the most popular programming languages currently. It looks like this trend is about to continue in 2021 and beyond. So, if you are a Python beginner, the best thing you can do is work on some real-time Python project ideas.

We, here at upGrad, believe in a practical approach as theoretical knowledge alone won’t be of help in a real-time work environment. In this article, we will be exploring some interesting Python project ideas which beginners can work on to put their Python knowledge to test. In this article, you will find 42 top python project ideas for beginners to get hands-on experience on Python

Moreover, project-based learning helps improve student knowledge. That’s why all of the upGrad courses cover case studies and assignments based on real-life problems. This technique is ideally for, but not limited to, beginners in programming skills.

But first, let’s address the more pertinent question that must be lurking in your mind:

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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:

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Real Time Vehicle Identifier and Speed counter using Python

Download Free Source code and complete tutorial of Real-time Vehicle Identifier and speed counter Using python and OpenCV. Some of the methods used to classify cars is to remember license plate numbers. The identification device for the license plate consists of three key parts: sensing, picture acquisition, and detection. Typically the component detecting the vehicle is focused on proximity or loop coil sensors and sends the signal to the component recording the picture to activate a video camera. After receiving the trigger signal from the sensing part, the image capturing part captures the image of the car using a high speed shutter to reduce blurring in motion. The portion of identification then scans the caught picture and identifies the numbers on the license plate.

Steps to Perform This Program

• Device Senses Vehicles
• Locate Plate Number
• The Character Segment
• Store Database Character

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Top Android Projects with Source Code

Android Projects with Source Code – Your entry pass into the world of Android

Hello Everyone, welcome to this article, which is going to be really important to all those who’re in dilemma for their projects and the project submissions. This article is also going to help you if you’re an enthusiast looking forward to explore and enhance your Android skills. The reason is that we’re here to provide you the best ideas of Android Project with source code that you can choose as per your choice.

These project ideas are simple suggestions to help you deal with the difficulty of choosing the correct projects. In this article, we’ll see the project ideas from beginners level and later we’ll move on to intermediate to advance.

Android Projects with Source Code

Before working on real-time projects, it is recommended to create a sample hello world project in android studio and get a flavor of project creation as well as execution: Create your first android project

Android Projects for beginners

1. Calculator

Android Project: A calculator will be an easy application if you have just learned Android and coding for Java. This Application will simply take the input values and the operation to be performed from the users. After taking the input it’ll return the results to them on the screen. This is a really easy application and doesn’t need use of any particular package.

To make a calculator you’d need Android IDE, Kotlin/Java for coding, and for layout of your application, you’d need XML or JSON. For this, coding would be the same as that in any language, but in the form of an application. Not to forget creating a calculator initially will increase your logical thinking.

Once the user installs the calculator, they’re ready to use it even without the internet. They’ll enter the values, and the application will show them the value after performing the given operations on the entered operands.

Source Code: Simple Calculator Project

2. A Reminder App

Android Project: This is a good project for beginners. A Reminder App can help you set reminders for different events that you have throughout the day. It’ll help you stay updated with all your tasks for the day. It can be useful for all those who are not so good at organizing their plans and forget easily. This would be a simple application just whose task would be just to remind you of something at a particular time.

To make a Reminder App you need to code in Kotlin/Java and design the layout using XML or JSON. For the functionality of the app, you’d need to make use of AlarmManager Class and Notifications in Android.

In this, the user would be able to set reminders and time in the application. Users can schedule reminders that would remind them to drink water again and again throughout the day. Or to remind them of their medications.

3. Quiz Application

Android Project: Another beginner’s level project Idea can be a Quiz Application in android. Here you can provide the users with Quiz on various general knowledge topics. These practices will ensure that you’re able to set the layouts properly and slowly increase your pace of learning the Android application development. In this you’ll learn to use various Layout components at the same time understanding them better.

To make a quiz application you’ll need to code in Java and set layouts using xml or java whichever you prefer. You can also use JSON for the layouts whichever preferable.

In the app, questions would be asked and answers would be shown as multiple choices. The user selects the answer and gets shown on the screen if the answers are correct. In the end the final marks would be shown to the users.

4. Simple Tic-Tac-Toe

Android Project: Tic-Tac-Toe is a nice game, I guess most of you all are well aware of it. This will be a game for two players. In this android game, users would be putting X and O in the given 9 parts of a box one by one. The first player to arrange X or O in an adjacent line of three wins.

To build this game, you’d need Java and XML for Android Studio. And simply apply the logic on that. This game will have a set of three matches. So, it’ll also have a scoreboard. This scoreboard will show the final result at the end of one complete set.

Upon entering the game they’ll enter their names. And that’s when the game begins. They’ll touch one of the empty boxes present there and get their turn one by one. At the end of the game, there would be a winner declared.

Source Code: Tic Tac Toe Game Project

5. Stopwatch

Android Project: A stopwatch is another simple android project idea that will work the same as a normal handheld timepiece that measures the time elapsed between its activation and deactivation. This application will have three buttons that are: start, stop, and hold.

This application would need to use Java and XML. For this application, we need to set the timer properly as it is initially set to milliseconds, and that should be converted to minutes and then hours properly. The users can use this application and all they’d need to do is, start the stopwatch and then stop it when they are done. They can also pause the timer and continue it again when they like.

6. To Do App

Android Project: This is another very simple project idea for you as a beginner. This application as the name suggests will be a To-Do list holding app. It’ll store the users schedules and their upcoming meetings or events. In this application, users will be enabled to write their important notes as well. To make it safe, provide a login page before the user can access it.

So, this app will have a login page, sign-up page, logout system, and the area to write their tasks, events, or important notes. You can build it in android studio using Java and XML at ease. Using XML you can build the user interface as user-friendly as you can. And to store the users’ data, you can use SQLite enabling the users to even delete the data permanently.

Now for users, they will sign up and get access to the write section. Here the users can note down the things and store them permanently. Users can also alter the data or delete them. Finally, they can logout and also, login again and again whenever they like.

7. Roman to decimal converter

Android Project: This app is aimed at the conversion of Roman numbers to their significant decimal number. It’ll help to check the meaning of the roman numbers. Moreover, it will be easy to develop and will help you get your hands on coding and Android.

You need to use Android Studio, Java for coding and XML for interface. The application will take input from the users and convert them to decimal. Once it converts the Roman no. into decimal, it will show the results on the screen.

The users are supposed to just enter the Roman Number and they’ll get the decimal values on the screen. This can be a good android project for final year students.

8. Virtual Dice Roller

Android Project: Well, coming to this part that is Virtual Dice or a random no. generator. It is another simple but interesting app for computer science students. The only task that it would need to do would be to generate a number randomly. This can help people who’re often confused between two or more things.

Using a simple random number generator you can actually create something as good as this. All you’d need to do is get you hands-on OnClick listeners. And a good layout would be cherry on the cake.

The user’s task would be to set the range of the numbers and then click on the roll button. And the app will show them a randomly generated number. Isn’t it interesting ? Try soon!

9. A Scientific Calculator App

Android Project: This application is very important for you as a beginner as it will let you use your logical thinking and improve your programming skills. This is a scientific calculator that will help the users to do various calculations at ease.

To make this application you’d need to use Android Studio. Here you’d need to use arithmetic logics for the calculations. The user would need to give input to the application that will be in terms of numbers. After that, the user will give the operator as an input. Then the Application will calculate and generate the result on the user screen.

10. SMS App

Android Project: An SMS app is another easy but effective idea. It will let you send the SMS to various no. just in the same way as you use the default messaging application in your phone. This project will help you with better understanding of SMSManager in Android.

For this application, you would need to implement Java class SMSManager in Android. For the Layout you can use XML or JSON. Implementing SMSManager into the app is an easy task, so you would love this.

The user would be provided with the facility to text to whichever number they wish also, they’d be able to choose the numbers from the contact list. Another thing would be the Textbox, where they’ll enter their message. Once the message is entered they can happily click on the send button.

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