Slicing mixin

The slicing mixin adds the ability to index an NDData object in a manner similar to a numpy array. Slicing returns a new NDData object with the shape indicated by the slice.

The first step in creating an NDData-based object with slicing is to create a new class:

>>> from astropy.nddata import NDData, NDSlicingMixin
>>> class MyNDDataWithSlicing(NDSlicingMixin, NDData): pass

Then, initialize the new object the same way you would initialize a plain NDData object:

>>> sliceable_ndd = MyNDDataWithSlicing([1, 2, 3, 4])
>>> sliceable_ndd[1:3]
MyNDDataWithSlicing([2, 3])

One important note: the order you list the mixins and NDData matters; the base class, NDData should be on the far right.