Update 15 sept 2020

I found these wheel builds from Thomas Viehmann that worked very well on a rpi4 64 bit running python 3.7. They are pytorch 1.6.0 and avoids the original hacks. Only issue was that my camera stopped working, but manage to circumvent it by using a different driver (v4l-utils) and using opencv’s VideoCapture() to get images. Got it running in a docker image with the following (removed some parts that I dont think is necessary):

(the balena docker image is a fairly stripped down ubuntu image)

FROM balenalib/raspberrypi4-64:latest
# Defines our working directory in container
WORKDIR /usr/src/app
RUN sudo apt-get update
RUN apt-get install -y gcc python3-dev v4l-utils python3-opencv python3-pip python3-setuptools libffi-dev libssl-dev

# PYTORCH: 
RUN wget https://mathinf.com/pytorch/arm64/torch-1.6.0a0+b31f58d-cp37-cp37m-linux_aarch64.whl
RUN wget https://mathinf.com/pytorch/arm64/torchvision-0.7.0a0+78ed10c-cp37-cp37m-linux_aarch64.whl
RUN sudo apt-get install -y python3-numpy python3-wheel python3-setuptools python3-future python3-yaml python3-six python3-requests python3-pip python3-pillow
RUN pip3 install torch*.whl torchvision*.whl

Original Post

Earlier this year I had to install pytorch on a raspiberry pi for my robotic lawn mower project (more on that later). However, the process was very painful, so Ill throw my notes here in case anyone else tries to do the same. Its not supposed to be bullet-proof, but may help with some pointers. Updates to this proceudre may be found here.

Installed from wheel on these: https://github.com/nmilosev/pytorch-arm-builds

But for rpi4 there was some errors, so I installed a wheel after reading this comment: https://github.com/nmilosev/pytorch-arm-builds/issues/4#issuecomment-527433112

Install from his wheel a bit longer down the thread, and rename those _C.**.so and _d.**.so files to _C.so and _d.so.

Torchvision works, but Pillow 7.0.0 was too new, so downgraded to 6.1 after some random comments I found.

Step-by-step:

PIP install pytorch from wheel

Download wheel from here https://github.com/nmilosev/pytorch-arm-builds and run sudo pip3 install torch-1.1.0-cp37-cp37m-linux_armv7l.whl

Rename some files

Then if you try to run sudo python3 -c "import torch" you get:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/local/lib/python3.7/dist-packages/torch/__init__.py", line 79, in <module>
    from torch._C import *
ModuleNotFoundError: No module named 'torch._C'

Can be fixed by the following:

cd /usr/local/lib/python3.7/dist-packages/torch
sudo mv _C.cpython-37m-arm-linux-gnueabi.so _C.so
sudo mv _dl.cpython-37m-arm-linux-gnueabi.so _dl.so