How do I find the name of the conda environment in which my code is running?

问题

I'm looking for a good way to figure out the name of the conda environment I'm in from within running code or an interactive python instance.

The use-case is that I am running Jupyter notebooks with both Python 2 and Python 3 kernels from a miniconda install. The default environment is Py3. There is a separate environment for Py2. Inside the a notebook file, I want it to attempt to conda install foo. I'm using subcommand to do this for now, since I can't find a programmatic conda equivalent of pip.main(['install','foo']).

The problem is that the command needs to know the name of the Py2 environment to install foo there if the notebook is running using the Py2 kernel. Without that info it installs in the default Py3 env. I'd like for the code to figure out which environment it is in and the right name for it on its own.

The best solution I've got so far is:

import sys

def get_env():
    sp = sys.path[1].split("/")
    if "envs" in sp:
        return sp[sp.index("envs") + 1]
    else:
        return ""

Is there a more direct/appropriate way to accomplish this?

回答1:

You want $CONDA_DEFAULT_ENV or $CONDA_PREFIX:

$ source activate my_env
(my_env) $ echo $CONDA_DEFAULT_ENV
my_env

(my_env) $ echo $CONDA_PREFIX
/Users/nhdaly/miniconda3/envs/my_env

$ source deactivate
$ echo $CONDA_DEFAULT_ENV  # (not-defined)

$ echo $CONDA_PREFIX  # (not-defined)

In python:

In [1]: import os
   ...: print os.environ['CONDA_DEFAULT_ENV']
   ...:
my_env

---

The environment variables are not well documented. You can find CONDA_DEFAULT_ENV mentioned here: https://www.continuum.io/blog/developer/advanced-features-conda-part-1

The only info on CONDA_PREFIX I could find is this Issue: https://github.com/conda/conda/issues/2764

回答2:

I am using this:

import sys
sys.executable.split('/')[-3]

it has the advantage that it doesn't assume the env is in the path (and is nested under envs). Also, it does not require the environment to be activated via source activate.

Edit: If you want to make sure it works on Windows, too:

import sys
from pathlib import Path
Path(sys.executable).as_posix().split('/')[-3]

To clarify: sys.executable gives you the path of the current python interpreter (regardless of activate/deactivate) -- for instance '/Users/danielsc/miniconda3/envs/nlp/bin/python'. The rest of the code just takes the 3rd from last path segment, which is the name of the folder the environment is in, which is usually also the name of the python environment.

回答3:

very simply, you could do

envs = subprocess.check_output('conda env list').splitlines()
active_env = list(filter(lambda s: '*' in str(s), envs))[0]
env_name = str(active_env).split()[0]

回答4:

Edit: Oops, I hadn't noticed Ivo's answer. Let's say that I am expanding a little bit on it.

---

If you run your python script from terminal:

import os
os.system("conda env list")

This will list all conda environments, as from terminal with conda env list.

Slightly better:

import os
_ = os.system("conda env list | grep '*'")

The _ = bit will silence the exist status of the call to os.system (0 if successful), and grep will only print out the line with the activated conda environment.

If you don't run your script from terminal (e.g. it is scheduled via crontab), then the above won't have anywhere to "print" the result. Instead, you need to use something like python's subprocess module. The simplest solution is probably to run:

import subprocess
output = subprocess.check_output("conda env list | grep '*'", shell=True, encoding='utf-8')
print(output)

Namely output is a string containing the output of the command conda env list, not its exit status (that too can be retrieved, see documentation of the subprocess module).

Now that you have a string with the information on the activated conda environment, you can perform whichever test you need (using regular expressions) to perform (or not) the installs mentioned in your question.

Remark.
Of course, print(output) in the block above will have no effect if your script is not run from terminal, but if you test the block in a script which you run from terminal, then you can verify that it gives you what you want. You can for instance print this information into a log file (using the logging module is recommended).

回答5:

Since similar searches related to 'how do I determine my python environment' leads to this answer I thought I will also mention a way I find out which environment I am currently running my code from. I check the location of my pip binary which points to a location within the current environment. By looking at the output of the following command you can easily determine which environment you are in. (Please note that this solution is not applicable if you have inherited pip packages from your global environment/other environment)

In Windows command prompt:

where pip

If you are inside a Jupyter Notebook add an exclamation mark(!) before the command to execute the command in your host command prompt:

in[10]: !where pip

The output will look something like this:

C:\Users\YourUsername\.conda\envs\YourEnvironmentName\Scripts\pip.exe
C:\ProgramData\Anaconda3\Scripts\pip.exe

YourEnvironmentName gives out the name of your current environment.

In Linux/Mac, you can use the which command instead of where: (Not tested).

For python3 environment

which pip3

From Jupyter notebook:

in[10]: !which pip3

This should directly point to the location within your current environment.

回答6:

On Windows (might work but untested on Linux):

import sys
import os

# e.g. c:\Users\dogbert\Anaconda3\envs\myenvironment
print( sys.exec_prefix.split(os.sep)[-1] )

Answers using environment variables or assuming the path separator is "/" didn't work in my Windows/Anaconda3 environment.

This assumes you are in an environment.

来源：https://stackoverflow.com/questions/36539623/how-do-i-find-the-name-of-the-conda-environment-in-which-my-code-is-running