class_weights cannot be passed via config file as a tensor is expected about torchgeo

[isaaccorley]

Care to make a PR to accept a list and convert to a tensor? If not then I can take it on this weekend.

[robmarkcole]

You will get to it way before me!

[adamjstewart]

For a bit of history, I added this in #1221 and it initially only supported lists. In #1413, @ntw-au modified this to support lists, numpy arrays, and torch tensors. Then in #1541, I modified it to only accept torch tensors. I agree we need a way to support class_weights in a YAML file (and preferably also on the command line). If omegaconf supports this, we could also easily enable omegaconf as a parser: https://lightning.ai/docs/pytorch/stable/cli/lightning_cli_advanced_2.html#enable-variable-interpolation.

[isaaccorley]

I haven't looked at the Lightning CLI in awhile but I wonder if it supports recursive instantiation like

class_weights:
   class_path: torch.tensor
   init_args:
      data: [0.5, 0.5]

[isaaccorley]

If you want to use it with hydra.utils.instantiate and omegaconf you would only need to do the following:

class_weights:
   _target_: torch.tensor
   data: [0.5, 0.5]