[Numpy-discussion] Iterate over all 1-dim views

Pauli Virtanen ptvirtan@elisanet...
Sun Oct 7 07:40:46 CDT 2007


Neal Becker <ndbecker2@gmail.com> kirjoitti: 
> Suppose I have a function F(), which is defined for 1-dim arguments.  If the
> user passes an n>1 dim array, I want to apply F to each 1-dim view.
> 
> For example, for a 2-d array, apply F to each row and return a 2-d result.
> 
> For a 3-d array, select each 2-d subarray and see above.  Return 3-d result.
> 
> Any suggestions on how to code something like this in numpy?

You may be looking for numpy.apply_along_axis:

>>> from numpy import *
>>> x=arange(2*3*4); x.shape=(2,3,4)
>>> x
array([[[ 0,  1,  2,  3],
        [ 4,  5,  6,  7],
        [ 8,  9, 10, 11]],

       [[12, 13, 14, 15],
        [16, 17, 18, 19],
        [20, 21, 22, 23]]])
>>> apply_along_axis(cumsum, 0, x)
array([[[ 0,  1,  2,  3],
        [ 4,  5,  6,  7],
        [ 8,  9, 10, 11]],

       [[12, 14, 16, 18],
        [20, 22, 24, 26],
        [28, 30, 32, 34]]])
>>> apply_along_axis(cumsum, 1, x)
array([[[ 0,  1,  2,  3],
        [ 4,  6,  8, 10],
        [12, 15, 18, 21]],

       [[12, 13, 14, 15],
        [28, 30, 32, 34],
        [48, 51, 54, 57]]])
>>> apply_along_axis(cumsum, 2, x)
array([[[ 0,  1,  3,  6],
        [ 4,  9, 15, 22],
        [ 8, 17, 27, 38]],

       [[12, 25, 39, 54],
        [16, 33, 51, 70],
        [20, 41, 63, 86]]])


-- 




More information about the Numpy-discussion mailing list