python 3.x - From conda create requirements.txt for pip3

Question

Hi I usually use conda to manage my environments, but now I am on a project that needs a little more horsepower than my laptop. So I am trying to use my university's workstations which have new Intel Xeons. But I don't have admin rights and the workstation does not have conda so I am forced to work with virtualenv and pip3.

How do I generate a requirements.txt from conda that will work with pip3 and venv?

conda list -e > requirements.txt

does not generate a compatible file:

= is not a valid operator. Did you mean == ?

The conda output is:

# This file may be used to create an environment using:
# $ conda create --name <env> --file <this file>
# platform: osx-64
certifi=2016.2.28=py36_0
cycler=0.10.0=py36_0
freetype=2.5.5=2
icu=54.1=0
libpng=1.6.30=1
matplotlib=2.0.2=np113py36_0
mkl=2017.0.3=0
numpy=1.13.1=py36_0
openssl=1.0.2l=0
pip=9.0.1=py36_1
pyparsing=2.2.0=py36_0
pyqt=5.6.0=py36_2
python=3.6.2=0
python-dateutil=2.6.1=py36_0
pytz=2017.2=py36_0
qt=5.6.2=2
readline=6.2=2
scikit-learn=0.19.0=np113py36_0
scipy=0.19.1=np113py36_0
setuptools=36.4.0=py36_1
sip=4.18=py36_0
six=1.10.0=py36_0
sqlite=3.13.0=0
tk=8.5.18=0
wheel=0.29.0=py36_0
xz=5.2.3=0
zlib=1.2.11=0

I thought I would just manually change all = to == but the there are two = in the conda output. Which one to change? Surely there is an easier way?

EDIT: pip freeze > requirements.txt gives:

certifi==2016.2.28
cycler==0.10.0
matplotlib==2.0.2
matplotlib-venn==0.11.5
numpy==1.13.1
pyparsing==2.2.0
python-dateutil==2.6.1
pytz==2017.2
scikit-learn==0.19.0
scipy==0.19.1
six==1.10.0

Answer 1

As the comment at the top indicates, the output of

conda list -e > requirements.txt

can be used to create a conda virtual environment with

conda create --name <env> --file requirements.txt

but this output isn't in the right format for pip.

If you want a file which you can use to create a pip virtual environment (i.e. a requirements.txt in the right format) you can install pip within the conda environment, the use pip to create requirements.txt.

conda activate <env>
conda install pip
pip freeze > requirements.txt

Then use the resulting requirements.txt to create a pip virtual environment:

python3 -m venv env
source env/bin/activate
pip install -r requirements.txt

When I tested this, the packages weren't identical across the outputs (pip included fewer packages) but it was sufficient to set up a functional environment.

For those getting odd path references in requirements.txt, use:

pip list --format=freeze > requirements.txt