python_tutorials/b07_Python7_venv.txt at master · lselector/python_tutorials · GitHub

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There are multiple ways to work with Python virtual environments.

Recommended way - use "venv" module.
    - included into standard python library since Python 3.3
    - subset of original virtualenv (except for support for python 2.* and some minor features)
    - endorsed by PyPA (Python Packaging Authority)
    - https://www.pypa.io/en/latest/
    - https://docs.python.org/3/tutorial/venv.html

Here are some commands from "venv" tutorial:
# --------------------------------------------------------------
cd
mkdir envs
cd envs
python3 -m venv tutorial-env

source tutorial-env/bin/activate        # in bash shell
source tutorial-env/bin/activate.fish   # in fish shell
tutorial-env\Scripts\activate.bat       # on Windows

cd tutorial-env

        ./bin
        ./include
        ./lib/python3.8/site-packages/pip

env | grep -i path

    PATH=/Users/levselector/envs/tutorial-env/bin:......
    _OLD_VIRTUAL_PATH=...

which python
    /Users/levselector/envs/tutorial-env/bin/python -> /Users/levselector/anaconda3/bin/python

which pip
    /Users/levselector/brett_env/bin/pip    # python script

You can run pip install commands, for example:

    python -m pip install novas
    python -m pip install requests==2.6.0
    python -m pip install --upgrade requests
    pip show requests
    pip list
    pip freeze > requirements.txt
    python -m pip install -r requirements.txt

you can restore previous default environment
and reset $PATH to original value

    deactivate

# --------------------------------------------------------------
Here are links for virtualenv, venv, and some other utilities:

  virtualenv
    - original tool written by Ian Bicking (who also wrote "pip")
    - https://www.ianbicking.org/
    - https://pypi.org/project/virtualenv/
    - https://virtualenv.pypa.io/en/latest/
    - https://www.youtube.com/watch?v=N5vscPTWKOk
    - https://github.com/pypa/virtualenv

  venv
    - included into standard python library since Python 3.3
    - endorsed by PyPA (Python Packaging Authority
    - https://www.pypa.io/en/latest/

  pyvenv
    - deprecated in Python 3.6

  pyenv
    - pure shell tool
    - https://github.com/pyenv/pyenv
    - https://k0nze.dev/posts/install-pyenv-venv-vscode/
    - https://github.com/pyenv/pyenv-virtualenv

  virtualenvwrapper
    - a set of extensions to Ian Bickings virtualenv tool
    - useful when you have many environments to switch between
    - https://virtualenvwrapper.readthedocs.io/en/latest/

  pipenv
    - combining pip and virtualenv into one command
    - https://github.com/pypa/pipenv

  conda
    - creates virtual environments under anaconda3/envs/

See some comparisons for example here:

https://stackoverflow.com/questions/41573587/what-is-the-difference-between-venv-pyvenv-pyenv-virtualenv-virtualenvwrappe

# --------------------------------------------------------------
conda offers its own mechanisms to manage virtual environments.
The environments will be created under the main anaconda directory,
for example:
   anaconda3/envs/myenv1/
   anaconda3/envs/myenv2/

It is OK to use it on your local machine.
But for environment with many developers, it is probably safer
to use "venv" instead of "conda", because with "venv" each
user will create his environments in separate directories as needed
and will not have to mess with the main anaconda directory.

Here are some "conda" commands:

https://conda.io/projects/conda/en/latest/user-guide/tasks/manage-environments.html

conda create --name myenv
conda create -n myenv python=3.6
conda create -n myenv scipy       # creates environment with specific package
conda create -n myenv scipy=0.15.0
conda create -n myenv python=3.6 scipy=0.15.0 astroid babel
conda create --no-default-packages -n myenv python
conda env create -f environment.yml

conda create -n myenv python
conda install -n myenv scipy=0.15.0

conda activate myenv # use "conda deactivate" to deactivate

conda env list
conda info --envs

conda create --prefix ./envs jupyterlab=0.35 matplotlib=3.1 numpy=1.16
conda activate ./envs

$ conda config --set env_prompt '({name})'
# This will edit your .condarc

conda env update --prefix ./env --file environment.yml  --prune

conda create --name myclone --clone myenv

conda list -n myenv
conda list -n myenv scipy
conda list
conda list --explicit
conda list --explicit > spec-file.txt
conda create --name myenv --file spec-file.txt

conda init --help
auto_activate_base: bool
conda activate base
conda activate --stack myenv
conda config --set auto_stack 1
conda config --set changeps1 false
conda config --set changeps1 true

conda install -n myenv pip
conda activate myenv
pip <pip_subcommand>

conda env config vars list
conda env config vars set my_var=value
conda env config vars unset my_var -n test-env
# --------------------------------------------------------------