Combining conda and google colab

Sometimes it’s necessary to downgrade packages in google colab to restore compatibility with an older version (e.g. pytorch). One way of doing this is using conda within colab and a few tricks make this work. Here is the colab notebook:

https://colab.research.google.com/drive/1W5UnflB8m1zo6lP1y11V78QczMRBI0FE?usp=sharing

Here a quick code gist:

#Check Python version of colab - we need to match this in conda:
!python --version

%%bash
MINICONDA_INSTALLER_SCRIPT=Miniconda3-py37_4.10.3-Linux-x86_64.sh
MINICONDA_PREFIX=/usr/local
wget https://repo.continuum.io/miniconda/$MINICONDA_INSTALLER_SCRIPT
chmod +x $MINICONDA_INSTALLER_SCRIPT
./$MINICONDA_INSTALLER_SCRIPT -b -f -p $MINICONDA_PREFIX

!which conda # should return /usr/local/bin/conda
!conda --version # should return 4.10.3
!python --version # should return 3.7.10 but should actually match the one installed in colab, which is currently: 3.7.11

%%bash
conda install --channel defaults conda python=3.7 --yes
conda update --channel defaults --all --yes

!conda --version # now returns 4.11.0
!python --version # now matches with colab :) 3.7.11

!yes | conda install pytorch==1.6.0 torchvision==0.7.0 -c pytorch

import sys
sys.path # dist-packages is colab and site-packages is conda -> problem is that colab packages get loaded before conda

sys.path.insert(0,"/usr/local/lib/python3.7/site-packages")

# So this will now use conda's torch with cuda 10
import torch
print(torch.version.cuda)