[Numpy-discussion] How to preserve number of array dimensions when taking a slice?
David Warde-Farley
dwf@cs.toronto....
Sat Aug 8 03:46:08 CDT 2009
On 8-Aug-09, at 12:53 AM, Dr. Phillip M. Feldman wrote:
>
> I'd like to be able to make a slice of a 3-dimensional array, doing
> something
> like the following:
>
> Y= X[A, B, C]
>
> where A, B, and C are lists of indices. This works, but has an
> unexpected
> side-effect. When A, B, or C is a length-1 list, Y has fewer
> dimensions than
> X. Is there a way to do the slice such that the number of dimensions
> is
> preserved, i.e., I'd like Y to be a 3-dimensional array, even if one
> or more
> dimensions is unity. Is there a way to do this?
Err, X[A, B, C] with A, B and C lists should always return a 1D array,
I think.
Lists of indices count as 'fancy indexing', not slicing. If using
slices, you can specify slices that are only 1 long as in X[5:6, :, :]
and retain the dimensionality.
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