[Numpy-discussion] slicing an n-dimensional array

Stefan van der Walt stefan at sun.ac.za
Wed Dec 3 19:02:21 EST 2014

Hi Catherine

On 2014-12-04 01:12:30, Moroney, Catherine M (398E) <Catherine.M.Moroney at jpl.nasa.gov> wrote:
> I have an array "A" of shape (NX, NY, NZ), and then I have a second array "B" of shape (NX, NY)
> that ranges from 0 to NZ in value.
> I want to create a third array "C" of shape (NX, NY) that holds the
> "B"-th slice for each (NX, NY)

Those two arrays can broadcast if you expand the dimensions of B:

A: (NX, NY, NZ)
B: (NX, NY, 1)

Your result would be

B = B[..., np.newaxis]  # now shape (NX, NY, 1)
C = A[B]

For more information on this type of broadcasting manipulation, see





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