No Numpy newaxis slicing support

[desplenterkarel]

Description:

H5py currently doesn't support adding np.newaxis when slicing a data array.

with h5py.File(file, 'r') as F:
        return F[array_group][:,np.newaxis,:,:]

as following return is given:

' File "", line 77, in read_hdf_frame_v1
return F[array_group][:,np.newaxis,:,:]
File "h5py_objects.pyx", line 54, in h5py._objects.with_phil.wrapper
File "h5py_objects.pyx", line 55, in h5py._objects.with_phil.wrapper
File "\lib\site-packages\h5py_hl\dataset.py", line 831, in getitem
selection = sel.select(self.shape, args, dataset=self)
File "****lib\site-packages\h5py_hl\selections.py", line 82, in select
return selector.make_selection(args)
File "h5py_selector.pyx", line 282, in h5py._selector.Selector.make_selection
File "h5py_selector.pyx", line 181, in h5py._selector.Selector.apply_args
TypeError: Selection can't process None'

'Summary of the h5py configuration

h5py 3.10.0
HDF5 1.14.2
Python 3.10.13 | packaged by Anaconda, Inc. | (main, Sep 11 2023, 13:24:38) [MSC v.1916 64 bit (AMD64)]
sys.platform win32
sys.maxsize 9223372036854775807
numpy 1.26.4
cython (built with) 0.29.36
numpy (built against) 1.21.6
HDF5 (built against) 1.14.2'

[tacaswell]

I am not sure that this is something we want to support as it is doing an implicit reshape as part of the read. I would expect:

    return F[array_group][:][:,np.newaxis,:,:]

would would and I think is clearer ("Please read the whole data set" and then "please resahpe it by sticking an extra axis in").

[aragilar]

I agree. I wonder if we should check for None earlier (e.g. in __getitem__) and raise a more helpful error?