conda

I recently started over with a fresh development environment and decided to try something new: I’m using Python 3 via miniconda. The first real hiccup I’ve run into is that conda’s environment activation/deactivation scheme only works in bash or zsh. I use fish. There is an open PR to get fish support for conda but in the meantime I hacked something together to help me out.

"Activating" a conda environment does a couple of things:

Puts the environment’s "bin" directory at the front of the PATH environment variable.
Sets a CONDA_DEFAULT_ENV environment variable that tells conda in which environment to do things when none is specified.
Adds the environment name to the prompt ala virtualenv.

Deactivating the environment resets everything to its pre-activation state. The fish functions I put together work like this:

~ > type python
python is /Users/---/miniconda3/bin/python
~ > condactivate env-name
(env-name) ~ > type python
python is /Users/---/miniconda3/envs/env-name/bin/python
(env-name) ~ > deactivate
~ > type python
python is /Users/---/miniconda3/bin/python

Here’s the text of the functions:

	function condalist -d 'List conda environments.'
	for dir in (ls $HOME/miniconda3/envs)
	echo $dir
	end
	end

	function condactivate -d 'Activate a conda environment' -a cenv
	if test -z $cenv
	echo 'Usage: condactivate <env name>'
	return 1
	end

	# condabin will be the path to the bin directory
	# in the specified conda environment
	set condabin $HOME/miniconda3/envs/$cenv/bin

	# check whether the condabin directory actually exists and
	# exit the function with an error status if it does not
	if not test -d $condabin
	echo 'Environment not found.'
	return 1
	end

	# deactivate an existing conda environment if there is one
	if set -q __CONDA_ENV_ACTIVE
	deactivate
	end

	# save the current path
	set -xg DEFAULT_PATH $PATH

	# put the condabin directory at the front of the PATH
	set -xg PATH $condabin $PATH

	# this is an undocumented environmental variable that influences
	# how conda behaves when you don't specify an environment for it.
	# https://github.com/conda/conda/issues/473
	set -xg CONDA_DEFAULT_ENV $cenv

	# set up the prompt so it has the env name in it
	functions -e __original_fish_prompt
	functions -c fish_prompt __original_fish_prompt
	function fish_prompt
	set_color blue
	echo -n '('$CONDA_DEFAULT_ENV') '
	set_color normal
	__original_fish_prompt
	end

	# flag for whether a conda environment has been set
	set -xg __CONDA_ENV_ACTIVE 'true'
	end

	function deactivate -d 'Deactivate a conda environment'
	if set -q __CONDA_ENV_ACTIVE
	# set PATH back to its default before activating the conda env
	set -xg PATH $DEFAULT_PATH
	set -e DEFAULT_PATH

	# unset this so that conda behaves according to its default behavior
	set -e CONDA_DEFAULT_ENV

	# reset to the original prompt
	functions -e fish_prompt
	functions -c __original_fish_prompt fish_prompt
	functions -e __original_fish_prompt
	set -e __CONDA_ENV_ACTIVE
	end
	end


	# aliases so condactivate and deactivate can have shorter names
	function ca -d 'Activate a conda environment'
	condactivate $argv
	end

	function cda -d 'Deactivate a conda environment'
	deactivate $argv
	end


	# complete conda environment names when activating
	complete -c condactivate -xA -a "(condalist)"
	complete -c ca -xA -a "(condalist)"

view raw conda.fish hosted with ❤ by GitHub

Or you can download it from https://gist.github.com/jiffyclub/9679788.

To use these, add them to the ~/.config/fish/ directory and source them from the end of the ~/.config/fish/config.fish file:

source $HOME/.config/fish/conda.fish

Pen and Pants

Don't Leave Home Without Them

State of Conda, Oct. 2014

Using Conda Environments and the Fish Shell