slice function incorrectly cross-linking in docs

[aaronmarkham]

Description

Sphinx is confused with the multiple entries for slice.
Cross-linking might be going to the wrong place. For example, https://mxnet.incubator.apache.org/api/python/ndarray/sparse.html#mxnet.ndarray.sparse.CSRNDArray.__setitem__ has a slice() reference that points to symbol but it would seem this should be going to ndarray.

Similar to the issue with NDArray and optimizer: #12829

Can this be fixed by something like #12886 ?

Here's the error:

/home/ubuntu/incubator-mxnet/python/mxnet/ndarray/ndarray.py:docstring of mxnet.ndarray.NDArray.__setitem__:None: WARNING: more than one target found for cross-reference u'slice': mxnet.symbol.Symbol.slice, mxnet.ndarray.sparse.CSRNDArray.slice, mxnet.symbol.sparse.slice, mxnet.ndarray.slice, mxnet.ndarray.NDArray.slice, mxnet.ndarray.sparse.slice, mxnet.symbol.slice
/home/ubuntu/incubator-mxnet/python/mxnet/ndarray/ndarray.py:docstring of mxnet.ndarray.NDArray.__getitem__:None: WARNING: more than one target found for cross-reference u'slice': mxnet.symbol.Symbol.slice, mxnet.ndarray.sparse.CSRNDArray.slice, mxnet.symbol.sparse.slice, mxnet.ndarray.slice, mxnet.ndarray.NDArray.slice, mxnet.ndarray.sparse.slice, mxnet.symbol.slice

Steps to reproduce

make html (from the docs folder)

[aaronmarkham]

@eric-haibin-lin - can you take a look... it seems part of this may have to do with the introduction of the sparse api.

[aaronmarkham]

Related error with sparse:

/home/ubuntu/incubator-mxnet/python/mxnet/ndarray/__init__.py:docstring of mxnet.ndarray.add:None: WARNING: more than one target found for cross-reference u'array': mxnet.ndarray.array, mxnet.ndarray.sparse.array
/home/ubuntu/incubator-mxnet/python/mxnet/ndarray/__init__.py:docstring of mxnet.ndarray.add:None: WARNING: more than one target found for cross-reference u'array': mxnet.ndarray.array, mxnet.ndarray.sparse.array
/home/ubuntu/incubator-mxnet/python/mxnet/ndarray/__init__.py:docstring of mxnet.ndarray.divide:None: WARNING: more than one target found for cross-reference u'array': mxnet.ndarray.array, mxnet.ndarray.sparse.array
/home/ubuntu/incubator-mxnet/python/mxnet/ndarray/__init__.py:docstring of mxnet.ndarray.divide:None: WARNING: more than one target found for cross-reference u'array': mxnet.ndarray.array, mxnet.ndarray.sparse.array
/home/ubuntu/incubator-mxnet/python/mxnet/ndarray/__init__.py:docstring of mxnet.ndarray.equal:None: WARNING: more than one target found for cross-reference u'array': mxnet.ndarray.array, mxnet.ndarray.sparse.array
/home/ubuntu/incubator-mxnet/python/mxnet/ndarray/__init__.py:docstring of mxnet.ndarray.equal:None: WARNING: more than one target found for cross-reference u'array': mxnet.ndarray.array, mxnet.ndarray.sparse.array
/home/ubuntu/incubator-mxnet/python/mxnet/ndarray/__init__.py:docstring of mxnet.ndarray.greater:None: WARNING: more than one target found for cross-reference u'array': mxnet.ndarray.array, mxnet.ndarray.sparse.array
/home/ubuntu/incubator-mxnet/python/mxnet/ndarray/__init__.py:docstring of mxnet.ndarray.greater:None: WARNING: more than one target found for cross-reference u'array': mxnet.ndarray.array, mxnet.ndarray.sparse.array
{and a lot more of this...}

[aaronmarkham]

And this one too:

/home/ubuntu/incubator-mxnet/python/mxnet/test_utils.py:docstring of mxnet.test_utils.rand_sparse_ndarray:None: WARNING: more than one target found for cross-reference u'dtype': mxnet.ndarray.sparse.CSRNDArray.dtype, mxnet.ndarray.sparse.RowSparseNDArray.dtype, mxnet.ndarray.NDArray.dtype

I can break this out as separate issues, but I get the feeling they're somewhat related around sparse.

[andrewfayres]

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