[Numpy-discussion] (no subject)

eat e.antero.tammi@gmail....
Sun Apr 22 04:54:12 CDT 2012


Hi,

On Fri, Apr 20, 2012 at 9:15 PM, Andre Martel <soucoupevolante@yahoo.com>wrote:

> What would be the best way to remove the maximum from a cube and
> "collapse" the remaining elements along the z-axis ?
> For example, I want to reduce Cube to NewCube:
>
> >>> Cube
> array([[[  13,   2,   3,  42],
>         [  5, 100,   7,   8],
>         [  9,   1,  11,  12]],
>
>        [[ 25,   4,  15,   1],
>         [ 17,  30,   9,  20],
>         [ 21,   2,  23,  24]],
>
>        [[ 1,   2,  27,  28],
>         [ 29,  18,  31,  32],
>         [ -1,   3,  35,   4]]])
>
> NewCube
>
> array([[[  13,   2,   3,  1],
>         [  5, 30,   7,   8],
>         [  9,   1,  11,  12]],
>
>        [[ 1,   2,  15,  28],
>         [ 17,  18,  9,  20],
>         [ -1,   2,  23,   4]]])
>
> I tried with argmax() and then roll() and delete() but these
> all work on 1-D arrays only. Thanks.
>
Perhaps it would be more straightforward to process via 2D-arrays, like:
In []: C
Out[]:
array([[[ 13,   2,   3,  42],
        [  5, 100,   7,   8],
        [  9,   1,  11,  12]],
       [[ 25,   4,  15,   1],
        [ 17,  30,   9,  20],
        [ 21,   2,  23,  24]],
       [[  1,   2,  27,  28],
        [ 29,  18,  31,  32],
        [ -1,   3,  35,   4]]])
In []: C_in= C.reshape(3, -1).copy()
In []: ndx= C_in.argmax(0)
In []: C_out= C_in[:2, :]
In []: C_out[:, ndx== 0]= C_in[1:, ndx== 0]
In []: C_out[1, ndx== 1]= C_in[2, ndx== 1]
In []: C_out.reshape(2, 3, 4)
Out[]:
array([[[13,  2,  3,  1],
        [ 5, 30,  7,  8],
        [ 9,  1, 11, 12]],
       [[ 1,  2, 15, 28],
        [17, 18,  9, 20],
        [-1,  2, 23,  4]]])

My 2 cents,
-eat

>
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