4D arrays

[Manolo Martínez]

On 12/01/15 at 06:47pm, Peter Otten wrote:
> Extract 2D arrays:
> 
> >>> a[:,2,3]
> array([[ 55,  56,  57,  58,  59],
>        [115, 116, 117, 118, 119]])
> >>> a[1,:,2]
> array([[ 70,  71,  72,  73,  74],
>        [ 90,  91,  92,  93,  94],
>        [110, 111, 112, 113, 114]])

The first one is equivalent to a[:, 2, 3, :], which is perhaps clearer
in this context: you are singling out row 2 in axis 1, and row 3 in axis
2, and taking everything from axes 0 and 3.

Mutatis mutandis with the second example and a[1, :, 2, :], which is
different from a[1, :, :, 2], etc.

Manolo