why can't I iterate through a union data set?

[brando90]

related to https://github.com/learnables/learn2learn/issues/355 I tried iterating through a union data set and couldn't.

odd the union data set's iterator doesn't work:

    assert isinstance(dataset, Dataset), f'Expect dataset to be of type Dataset but got {type(dataset)=}.'
    counts: dict = {}
    iter_dataset = iter(dataset)
    for datapoint in iter_dataset:
        x, y = datapoint

see:

Connected to pydev debugger (build 221.5080.212)
/Users/brandomiranda/opt/anaconda3/envs/meta_learning/lib/python3.9/site-packages/torchvision/datasets/mnist.py:498: UserWarning: The given NumPy array is not writeable, and PyTorch does not support non-writeable tensors. This means you can write to the underlying (supposedly non-writeable) NumPy array using the tensor. You may want to copy the array to protect its data or make it writeable before converting it to a tensor. This type of warning will be suppressed for the rest of this program. (Triggered internally at  ../torch/csrc/utils/tensor_numpy.cpp:180.)
  return torch.from_numpy(parsed.astype(m[2], copy=False)).view(*s)
Traceback (most recent call last):
  File "/Applications/PyCharm.app/Contents/plugins/python/helpers/pydev/pydevd.py", line 1491, in _exec
    pydev_imports.execfile(file, globals, locals)  # execute the script
  File "/Applications/PyCharm.app/Contents/plugins/python/helpers/pydev/_pydev_imps/_pydev_execfile.py", line 18, in execfile
    exec(compile(contents+"\n", file, 'exec'), glob, loc)
  File "/Users/brandomiranda/ultimate-utils/ultimate-utils-proj-src/uutils/torch_uu/dataset/concate_dataset.py", line 240, in <module>
    # check_cifar100_is_100_in_usl()
  File "/Users/brandomiranda/ultimate-utils/ultimate-utils-proj-src/uutils/torch_uu/dataset/concate_dataset.py", line 223, in check_mi_usl

  File "/Users/brandomiranda/ultimate-utils/ultimate-utils-proj-src/uutils/torch_uu/dataset/concate_dataset.py", line 102, in get_relabling_counts
    x, y = datapoint
TypeError: cannot unpack non-iterable NoneType object

[seba-1511]

Hey @brando90,

Is this for PyTorch's union dataset or learn2learn? Could you share an example on colab so I can take a look?

[seba-1511]

Closing since inactive.