# How to create a Python virtual environment on Lewis **URL:** \ **Category:** University of Missouri - Columbia\ **Created:** [June 23, 2020, 7:58pm UTC](https://ask.cyberinfrastructure.org/t/how-to-create-a-python-virtual-environment-on-lewis/1393 "2020-06-23T19:58:16Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![bjmfg8](https://ask.cyberinfrastructure.org/letter_avatar_proxy/v4/letter/b/ecb155/32.png) [@bjmfg8](https://ask.cyberinfrastructure.org/u/bjmfg8)\ **Post date:** [June 23, 2020, 7:58pm UTC](https://ask.cyberinfrastructure.org/t/how-to-create-a-python-virtual-environment-on-lewis/1393/1 "2020-06-23T19:58:16Z")
# Python Virtual Environments > (Python \>= 3.3) The `venv` module provides support for creating lightweight > “virtual environments” with their own site directories, optionally isolated > from system site directories. - (Python 3.3) Documentation: [https://docs.python.org/3.3/library/venv.html](https://docs.python.org/3.3/library/venv.html) - (Python 3.5) Documentation: [https://docs.python.org/3.5/library/venv.html](https://docs.python.org/3.5/library/venv.html) - (Python 3.6) Documentation: [https://docs.python.org/3.6/library/venv.html](https://docs.python.org/3.6/library/venv.html) * * * In the following examples, we will interactively install a Python Virtual Environment in our home folder using the preferred method for the version of Python used. We will install a Python Module, in this case NumPy. Please note that all work is done in an Interactive Slurm Job ## Usage (Python 3.5) For Python 3.3 to Python 3.5, the preferred tool for creating virtual environments is `pyvenv`. In this example, we will create a new virtual environment called `my_virtenv3` in our home folder: Command: ```bash module load python/python-3.5.2 pyvenv ~/my_virtenv3 ``` Output: ```bash [user@lewis4-c8k-hpc2-node279 ~]$ module load python/python-3.5.2 [user@lewis4-c8k-hpc2-node279 ~]$ pyvenv ~/my_virtenv3 [user@lewis4-c8k-hpc2-node279 ~]$ ``` Now that our new virtual environment is installed, we can activate using the `activate` script within our virtual environment. Once activated, your prompt will change to indicate what virtual environment you are using. You can also confirm what `python` and `pip` executables you are using via the `which` command: Command: ```bash source ~/my_virtenv3/bin/activate which pip which python ``` Output: ```bash [user@lewis4-c8k-hpc2-node279 ~]$ source ~/my_virtenv3/bin/activate (my_virtenv3) [user@lewis4-c8k-hpc2-node279 ~]$ which pip ~/my_virtenv3/bin/pip (my_virtenv3) [user@lewis4-c8k-hpc2-node279 ~]$ which python ~/my_virtenv3/bin/python (my_virtenv3) [user@lewis4-c8k-hpc2-node279 ~]$ ``` Optionally, you can now upgrade `pip`: Command: ```bash srun pip install --upgrade pip ``` Output: ```bash (my_virtenv3) [user@lewis4-c8k-hpc2-node279 ~]$ srun pip install --upgrade pip Collecting pip Using cached pip-9.0.1-py2.py3-none-any.whl Installing collected packages: pip Found existing installation: pip 8.1.1 Uninstalling pip-8.1.1: Successfully uninstalled pip-8.1.1 Successfully installed pip-9.0.1 (my_virtenv3) [user@lewis4-c8k-hpc2-node279 ~]$ ``` You can now install any needed python modules within you virtual environment: Command: ```bash srun pip install numpy ``` Output: ```bash (my_virtenv3) [user@lewis4-c8k-hpc2-node279 ~]$ srun pip install numpy srun: job 645607 queued and waiting for resources srun: job 645607 has been allocated resources Collecting numpy Downloading numpy-1.12.0-cp35-cp35m-manylinux1_x86_64.whl (16.8MB) Installing collected packages: numpy Successfully installed numpy-1.12.0 (my_virtenv3) [user@lewis4-c8k-hpc2-node279 ~]$ ``` To clear the virtual environment, use `deactivate`.: Command: ```bash deactivate ``` Output: ```bash (my_virtenv3) [user@lewis4-c8k-hpc2-node279 ~]$ deactivate [user@lewis4-c8k-hpc2-node279 ~]$ ``` ## Usage (Python 3.6) For Python 3.6, the `pyvenv` script has been deprecated in favor of using `python3 -m venv` to help prevent any potential confusion as to which Python interpreter a virtual environment will be based on. In this example, we will create a new virtual environment called `my_virtenv3.6.6` in our home folder: Command: ```bash module load python/python-3.6.6-tk python3 -m venv ~/my_virtenv3.6.6 ``` Output: ```bash [user@lewis4-c8k-hpc2-node279 ~]$ module load python/python-3.6.6-tk [user@lewis4-c8k-hpc2-node279 ~]$ python3 -m venv ~/my_virtenv3.6.6 [user@lewis4-c8k-hpc2-node279 ~]$ ``` Now that our new virtual environment is installed, we can activate using the `activate` script within our virtual environment. Once activated, your prompt will change to indicate what virtual environment you are using. You can also confirm what `python` and `pip` executables you are using via the `which` command: Command: ```bash source ~/my_virtenv3.6.6/bin/activate which pip which python ``` Output: ```bash [user@lewis4-c8k-hpc2-node279 ~]$ source ~/my_virtenv3.6.6/bin/activate (my_virtenv3.6.6) [user@lewis4-c8k-hpc2-node279 ~]$ which pip ~/my_virtenv3.6.6/bin/pip (my_virtenv3.6.6) [user@lewis4-c8k-hpc2-node279 ~]$ which python ~/my_virtenv3.6.6/bin/python (my_virtenv3.6.6) [user@lewis4-c8k-hpc2-node279 ~]$ ``` Optionally, you can now upgrade `pip`: Command: ```bash srun pip install --upgrade pip ``` Output: ```bash (my_virtenv3.6.6) [user@lewis4-c8k-hpc2-node279 ~]$ srun pip install --upgrade pip Requirement already up-to-date: pip in ./my_virtenv3.6.6/lib/python3.6/site-packages ``` You can now install any needed python modules within you virtual environment: Command: ```bash srun pip install numpy ``` Output: ```bash (my_virtenv3.6.6) [user@lewis4-c8k-hpc2-node279 ~]$ srun pip install numpy srun: job 645610 queued and waiting for resources srun: job 645610 has been allocated resources Collecting numpy Downloading numpy-1.12.0-cp36-cp36m-manylinux1_x86_64.whl (16.8MB) Installing collected packages: numpy Successfully installed numpy-1.12.0 (my_virtenv3.6.6) [user@lewis4-c8k-hpc2-node279 ~]$ ``` To clear the virtual environment, use `deactivate`.: Command: ```bash deactivate ``` Output: ```bash (my_virtenv3.6.6) [user@lewis4-c8k-hpc2-node279 ~]$ deactivate [user@lewis4-c8k-hpc2-node279 ~]$ ``` * * *