Virtual Environment for Python Workspace Part 2/3 conda

How to create virtual environment in Python using conda.

Nuhil Mehdy

7 minute read

Hope you already got the idea behind the necessity of virtual environment in Python ecosystem in my previous post. So, in this post I will directly go into the detail of conda  and its usage.

What is conda?

Just like virtualenv , this is also a package, dependency & environment management tool. Unlike virtualenv , conda  can work not only with Python but also with R, Javascript, Ruby, Lua, Scala etc. But, we will only focus on Python ecosystem for the sake of this series.

There are some significant benefits of conda  over virtualenv . For example - in its default configuration, conda  can install and manage thousand of packages at repo.continuum.io that are built, reviewed and maintained by Anaconda. Also, conda  can be combined with Continous Integration tools for better test & deployment.

How to install conda?

The easiest way to get conda  is to install miniconda . Yes, its sounds like Anaconda. But we don’t need to install that big fat ready-made environment. Rather we can install miniconda  that will come with conda  as package manager and its dependencies and the Python. By the way,

You do not need to uninstall other Python installations or packages in order to use conda. Even if you already have a system Python, another Python installation from a source such as the macOS Homebrew package manager and globally installed packages from pip such as pandas and NumPy, you do not need to uninstall, remove, or change any of them before using conda.

So, just download miniconda  from here and install in your system. You can choose either Python 2.X or Python 3.X version (I prefer to install miniconda  of Python 3.X version). We will talk about that very soon. The installer will add the conda  installation of Python to your PATH environment variable. To verify that conda  is installed successfully, issue the following command.

conda --version

Creating Virtual Environment

Before creating an environment, please keep in mind that, there are two variants of the installer: Miniconda is Python 2.X based and Miniconda3 is Python 3.X based. Note that the choice of which Miniconda is installed only affects the root environment. Regardless of which version of Miniconda you install, you can still install both Python 2.x and Python 3.x based environments.

Suppose you installed Python 3.X version of Miniconda and then if you issue the following command to create an environment,

conda create -n myenv python

the environment will be created based on Python 3.X version. On the other hand if you issue the following command, it will create a virtual environment based on Python 2.X.

conda create -n mypy2env python=2

Anyway, for now, forget about the mypy2env . Let’s activate the myenv  environment and start using that.

Activating an Environment

To activate the new environment, run the appropriate command for your operating system:

  • Linux and macOS: source activate myenv
  • Windows: activate myenv

As my miniconda  version was of Python 3.X version and I created the environment myenv  with default Python, so this environment is based on Python 3.X. We can also check that by activating and running the Python REPL in it, maybe. Just check out the following Terminal activity and hope you will get it :)

Nuhils-MacBook-Pro:~ nuhil$ source activate myenv

(myenv) Nuhils-MacBook-Pro:~ nuhil$ python
Python 3.6.2 |Continuum Analytics, Inc.| (default, Jul 20 2017, 13:14:59) 
[GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.57)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>>

Type exit()  in the above REPL to quit it and simply get back to the environment.

Deactivating an Environment

Deactivating an environment is as simple as issuing the following command,

source deactivate

So, the above command will deactivate the myenv  environment. Oh, by the way, before deactivating, let’s check which packages are installed in this new virtual environment by the following command:

(myenv) Nuhils-MacBook-Pro:~ nuhil$ conda list
# packages in environment at /Users/nuhil/miniconda3/envs/myenv:
#
certifi                   2016.2.28                py36_0  
openssl                   1.0.2l                        0  
pip                       9.0.1                    py36_1  
python                    3.6.2                         0  
readline                  6.2                           2  
setuptools                36.4.0                   py36_1  
sqlite                    3.13.0                        0  
tk                        8.5.18                        0  
wheel                     0.29.0                   py36_0  
xz                        5.2.3                         0  
zlib                      1.2.11                        0

Want to install packages in this virtual environment for your next project?

Managing Packages in an Environment

If you want to install packages using the conda  package manager then it can be done simply by conda install <packagename> . For example, let’s install the package beautifulsoup4  in the environment myenv :

conda install beautifulsoup4

A good thing about conda  package manager is that, if you don’t find a package using conda install  then you can look into Anaconda.org which is another product of the same vendor of miniconda and Anaconda. For example, to install the package bottleneck , you can issue the following command:

conda install --channel https://conda.anaconda.org/pandas bottleneck

Keep in mind that, you have to search for the desired package in the Anaconda.org site and there you will get the appropriate installation command for conda .

pip in conda

If you don’t find a package in conda or in Anaconda.org, then still you can install the package inside this conda  virtual environment by pip . Using pip  will download and install the package from Python’s official package repository PyPI. For example, let’s install numpy  in this virtual environment by the following command:

pip install numpy

Now, let’s check the packages that are installed so far in the environment by the following command again:

conda list

which will show something like following:

(myenv) Nuhils-MacBook-Pro:~ nuhil$ conda list
# packages in environment at /Users/nuhil/miniconda3/envs/myenv:
#
beautifulsoup4            4.6.0                    py36_0  
certifi                   2016.2.28                py36_0  
numpy                     1.13.3                    <pip>
openssl                   1.0.2l                        0  
pip                       9.0.1                    py36_1  
python                    3.6.2                         0  
readline                  6.2                           2  
setuptools                36.4.0                   py36_1  
sqlite                    3.13.0                        0  
tk                        8.5.18                        0  
wheel                     0.29.0                   py36_0  
xz                        5.2.3                         0  
zlib                      1.2.11                        0

In the above output, we can see that both beautifulsoup4  & numpy  exist together, though we installed beautifulsoup4  using conda  from their repository and numpy  from PyPI using pip .

Removing an Environment

Before removing any environment, you need to see all existing conda environments, right? For that, simply issue the following command which will show you all the existing virtual environments made by conda:

Nuhils-MacBook-Pro:~ nuhil$ conda info --envs
# conda environments:
#
myenv                    /Users/nuhil/miniconda3/envs/myenv
mypy2env                 /Users/nuhil/miniconda3/envs/mypy2env
root                  *  /Users/nuhil/miniconda3

Lets, remove the mypy2env  which we don’t want to use.

conda remove --name mypy2env --all

Sharing Environment to Other

Say, you have prepared a very good Python environment with all the necessary packages installed in it and made sure that the environment is working fine for your project/app. Now, you want to share this ready-made environment with your friend who is struggling to prepare such an environment where he wants to work on the same Python project/app. Yes, you can do that by simply exporting your environment configuration in a file and sharing that file with your friend.

First, you need to activate the environment you want to share. Then, to export our myenv  environment’s configuration, issue the following command:

(myenv) Nuhils-MacBook-Pro:~ nuhil$ conda env export > environment.yml

So, the shareable file is called environment.yml  and want to see whats in this file? It should contain something like following:

name: myenv
channels:
- defaults
dependencies:
- beautifulsoup4=4.6.0=py36_0
- certifi=2016.2.28=py36_0
- openssl=1.0.2l=0
- pip=9.0.1=py36_1
- python=3.6.2=0
- readline=6.2=2
- setuptools=36.4.0=py36_1
- sqlite=3.13.0=0
- tk=8.5.18=0
- wheel=0.29.0=py36_0
- xz=5.2.3=0
- zlib=1.2.11=0
- pip:
  - numpy==1.13.3
prefix: /Users/nuhil/miniconda3/envs/myenv

Pretty self-explanatory, right? Now, you can share this file to your friend and if your friend wants to prepare such a ready-made virtual environment, then he needs to install conda  first and the issue the following command:

conda env create -f environment.yml

conda is the package manager. Anaconda is a set of about a hundred packages including conda, numpy, scipy, ipython notebook, and so on. Did you know, Once you have Miniconda, you can easily install Anaconda into it with conda install anaconda ?

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