ENH: Explicitly show keys of .npz file in repr #23319
Description
Proposed new feature or change:
Determining the structure of npz files could be made more intuitive by providing info about keys. A quick example:
>>> np.savez("example.npz", x=np.arange(10), y=np.arange(3)) # An example file with multiple keys
>>> data = np.load("example.npz")
# NpzFile repr doesn't provide info about what the file contains
>>> data
<numpy.lib.npyio.NpzFile at 0x7fbd182567a0>
# Keys returns a KeysView as expected with Python dict-likes, but
# the KeysView repr isn't particularly informative
>>> data.keys()
KeysView(<numpy.lib.npyio.NpzFile object at 0x7fbd182567a0>)
# In order to get explicit info about the key, users have to
# know how to inspect this object
>>> list(data.keys())
['x', 'y']
# or,
>>> list(data)
['x', 'y']I think the user experience with .npz files would be improved by including explicit info about the keys in the NpzFile repr.