(Note: I am assuming familiarity with virtualenv and conda, and a general agreement that
using them are Good Things. See
here and
here,
respectively, if you want an introduction, or to be convinced.)
My new day job is on python 3.5.2,
PyMC3 runs on 2.7 and 3.6, and
supports both pip and conda installations, and my
personal projects
are all over the place, but I think I have a great and simple set up for having sane and explicit
control of all the versions and dependencies.
The short version
I want to have bash functions for
- new virtualenvs (
vn), - activating virtualenvs (
va), - deactivating virtualenvs (
vd), and - ddeleting virtualenvs (
vdd),
along with pyenv for handling the
version of python I am using, and
pyenv-virtualenv because
pyenv does not play that well with conda.
How to set it up!
$ brew install pyenv pyenv-virtualenv
Then add to ~/.bashrc:
# virtualenv aliases
function virtualenv_name { echo "${PWD##*/}" ; }
function vn { pyenv virtualenv "$(virtualenv_name)" ; }
function va { pyenv activate "$(virtualenv_name)" ; }
alias vd="pyenv deactivate"
function vdd { pyenv uninstall "$(virtualenv_name)" ; }
# sets up pyenv and pyenv-virtualenv
export PYENV_ROOT=/usr/local/var/pyenv
if which pyenv > /dev/null; then eval "$(pyenv init -)"; fi
if which pyenv-virtualenv > /dev/null; then eval "$(pyenv virtualenv-init -)"; fi
This allows me to set up a new project with, for example
$ mkdir my_new_project
$ cd my_new_project
$ pyenv local 3.6.3
$ vn
Requirement already satisfied: setuptools in /usr/local/var/pyenv/versions/3.6.3/envs/my_new_project/lib/python3.6/site-packages
Requirement already satisfied: pip in /usr/local/var/pyenv/versions/3.6.3/envs/my_new_project/lib/python3.6/site-packages
$ va
$ (my_new_project) pip install whatever
If I had wanted a conda version, I could have used pyenv local anaconda3-4.3.1 instead.
Note that your virtual environment is always the name of the directory you are in, and you cannot
have two different virtual environments in the same folder. I usually only develop PyMC3 using
Python 3, and use travis and experience to make sure it works on Python 2. If something is
funky though, I can delete one environment, swap to Python 2.7, and rebuild a fresh one to debug.
As an aside, pyenv does an incredible job of keeping up with the latest Python releases - the alpha candidate for Python 3.7.0 was up a day after it was released.