Python Virtual Environment – Venv and VirtualEnv – Why it is important.?

When we working on Simple Python scripting projects basic approach is to install Python on your machine, install all your required libraries via the terminal, write all your code in a single .py file or notebook, and run your Python program in the terminal. Moreover this is the common method for beginners.

But while we developing complex software projects like building a python library, an API, or software development kit, often you will be working with multiple files, multiple packages, and dependencies. You will need to isolate your Python development environment for that particular project.

Why We Use Virtual Environment. ?

May be you already got an idea from the above, why virtual environment is so important in python. Let’s consider a scenario, you are working for a different web based   python project ProjectA and ProjectB. ProjectA minimum requirement is Django version 1.9 and using your pip install, the package installed in your global python library. ProjectA working fine now.

ProjectB require also the same package Django but different version, let’s say version 1.10, which has some breaking changes between version 1.0 and 2.0. If you pip install to global python library the existing version 1.0 will update to 2.0 and when you run the ProjectA you may face error.

So what the above scenario teaching us is isolation of packages will resolve the problem and that’s exactly what virtual environment is.

We can have multiple virtual environments with different python versions, and it will be isolated python, packages, scripts from other virtual environments and your system.

VirtualEnv And Venv

VirtualEnv is tool to create virtual environment is Python 2 and Venv is the same for Python 3.xx. Both tool will create a folder which contains all the necessary executable to use the packages that a Python project would need.

Installing Virtualenv

Open ‘command prompt’, navigate to your directory using ‘cd’ command. then follow below.

pip install virtualenv

or use below code to install specifically for python 2

py -2 -m pip install virtualenv

To Test your installation.

virtualenv --version


Create a Virtualenv

virtualenv myDirectory

or use below code by mentioning python 2
specifically.

py -2 -m virtualenv myDirectory

After running the command a directory called ‘myDirectory’ will be created with all the necessary executable to use the
packages that a Python 2 project would need.
Activate virtualenv
Navigate to the directory we created for virtualenv using ‘cd’ command.

> cd myDirectory
> Source\activate
(myDirectory)>


After activation, install the required packages using pip install. 

Deactivate virtualenv
Just type ‘deactivate’ and exit from the virtualenv.

(myDirectory)> deactivate


Installing Venv
Open ‘command prompt’, navigate to your directory using ‘cd’ command. then follow below.
pip install venv

or use below code to install specifically for python 3.xx

py -3 -m pip install virtualenv


To Test your installation.

venv --version

Create a Venv

venv myDirectory


or use below code by mentioning python 3.xx specifically.

py -3 -m virtualenv myDirectory


After running the command a directory called ‘myDirectory’ will be created with all the necessary executable to use the
packages that a Python 3.xx project would need.
Activate Venv
Navigate to the directory we created for virtualenv using ‘cd’ command.

> cd myDirectory
> Source\activate
(myDirectory)>



After activation, install the required packages using pip install. 
Deactivate Venv
Just type ‘deactivate’ and exit from the venv.


(myDirectory)> deactivate


Conclusion
Both virtualenv and venv using for same thing but the python version will be different.
AS the python 2 already reached to end of life stage, it is no longer recommended to using
virtualenv. Use venv with python 3 instead.