Python Virtual Environments

venv.md

Create the virtual environment

The parameter env indicates the name of the environment, you can use any name you like instead of using env.

python3 -m venv env

Activate the virtual environment

source env/bin/activate

Confirm you're in the environment

This should point to .../env/bin/python

which python

Convert environment.yml into requirements.txt for pip usage

Okay, this is wrong and stupid but it works. This is a One-Liner that reads environment.yml and converts it into a proper formatted dependency file for pip.

python -c "import base64; exec(base64.decodebytes(b'aW5kZXggPSBOb25lCmYgICAgID0gb3BlbigiZW52aXJvbm1lbnQueW1sIiwgInIiKS5yZWFkKCku\nc3BsaXRsaW5lcygpCgpmb3IgbGluZSBpbiBmOgogICAgaWYgbGluZS5zdGFydHN3aXRoKCdkZXBl\nbmRlbmNpZXMnKToKICAgICAgICBpbmRleCA9IGYuaW5kZXgobGluZSkrMQogICAgICAgIGJyZWFr\nCgppZiBpbmRleDoKICAgIHdpdGggb3BlbigicmVxdWlyZW1lbnRzLnR4dCIsICJ3IikgYXMgbzoK\nICAgICAgICBmb3IgbGluZSBpbiBmW2luZGV4Ol06CiAgICAgICAgICAgIG8ud3JpdGUoIiA9PSAi\nLmpvaW4obGluZS5zcGxpdCgiLSIpWy0xXS5zdHJpcCgpLnNwbGl0KCI9IilbOjJdKSArICJcbiIp\nCgpwcmludCgiZG9uZS4iKQ=='))"

Here's the content of that suspicious looking base64-encoded string:

index = None
f     = open("environment.yml", "r").read().splitlines()

for line in f:
    if line.startswith('dependencies'):
        index = f.index(line)+1
        break

if index:
    with open("requirements.txt", "w") as o:
        for line in f[index:]:
            o.write(" == ".join(line.split("-")[-1].strip().split("=")[:2]) + "\n")

print("done.")

Dectivate the virtual environment

deactivate