How to Create and Manage Conda or Anaconda Virtual Environments on Linux Ubuntu

What is explained in this tutorial: In this tutorial, we explain how to create, modify, and erase Conda or Anaconda virtual environments on Linux Ubuntu.  The material presented in this tutorial is very important for disciplined Python software development on Linux Ubuntu.

Motivation: A lot of people who are starting to learn Python tend to install packages by using pip install without worrying too much about reproducibility of their code, package versions, package version conflicts, and the fact that by often calling pip install in the base Python environment (default Python environment) they might change the package versions and dependencies that might render some other code non-functional.

Creating a Conda virtual environment and installing all the packages in this virtual environment is a proper way of addressing these and similar problems. In fact, it is a standard Python programming practice to first create a Python virtual environment (either by using native Python environments or Anaconda), and then install all the packages.

The YouTube tutorial is given below.

First, you have to make sure that Conda or Anaconda are installed on your system. To install them, follow this tutorial. Secondly, you need to verify the installation. To do that, open a terminal and type

conda

If conda is installed on your system, you should get a description of all conda commands. Let us create a test folder

cd ~
mkdir testConda
cd testConda

Inside of this folder let us create our first Anaconda virtual environment. The general syntax for the Anaconda virtual environments is

conda create --name <my-env>

For example, to create a Conda virtual environment called “my_first”, type this

conda create --name my_first

You will be asked to confirm the creation and press “y”. To activate the environment, you need to type this

conda activate my_first

The next step is to install the packages. Whenever you can, try to install packages in a Conda virtual environment with “conda install”. Sometimes it is not possible to install some packages using conda install. Then you need to install the packages using the standard Python command pip install. Note that you will also need to install pip since it does not come by default with a newly created Anaconda environment.

To search for a package in a Conda virtual environment, type this:

conda search scypi
conda search numpy

You will see a list of all packages. To install a package, type this

conda install scipy
conda install numpy

To install a specific package version, type this

conda install curl=8.9.1

To check all the installed packages in the current virtual environment, type this

conda list

However, sometimes you need to install packages by using pip install. First make sure that pip is installed by typing this

conda install pip

Then, you can also list some of the packages by using pip list

pip list

Next, let us write a simple program and execute it inside of the environment

sudo nano test1.py

The code should look like this

import numpy as np

A=np.matrix([[1,2],[3,4]])
B=np.matrix([[0,-1],[1,0]])

C=np.matmul(A,B)

print(C)

Before we execute this code, let us make sure that we are running the python interpreter inside of the virtual environment. To do that, type this

which pyhon3

The output should look like this:

/home/ahaber/anaconda3/envs/my_first/bin/python3

This means that we are executing the Python interpreter inside of the virtual environment.

To run the Python file, type this

python3 test1.py

Next, let us deactivate the environment. To do that, type this

conda deactivate

Next, let us learn how to erase the environment. You can do that automatically or manually. To do that automatically, let us run this command that will list all the environments

conda env list

# conda environments:
#
base                   /home/ahaber/anaconda3
aloha                  /home/ahaber/anaconda3/envs/aloha
my_first               /home/ahaber/anaconda3/envs/my_first

To remove a specific environment, you need to type this:

conda remove --name <name of the environment> --all

For example, to remove the environment called my_first, you need to type this

conda remove --name my_first --all

To verify that the environment was removed, you need to type this

conda info --envs

or

conda env list

Finally, let us learn how to create a Conda environment with a specific Python version. To do that, we need to type this

conda create -n myenv python=3.9

Here, we are creating a conda environment with the Python version 3.9. To verify that the correct Python version is installed type this

conda activate myenv

python3 --version

And you should get the Python version 3.9. Next, let us deactivate and erase

conda deactivate

conda env list
conda remove --name myenv --all

conda env list