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The referenced challenge was inspired by the example given in PDL::Broadcasting, especially by the usage of range. Accordingly my own solution looks similar to the example:

use strict; use warinings; use PDL; use PDL::NiceSlice; sub submatrix_sum { my $m = pdl @_; $m->range(ndcoords($m(1:,1:)), 2)->reorder(2, 3, 0, 1) ->clump(2)->sumover; }

It can easily be extended to WxH submatrices:

sub submatrix_sum { my $w = shift; my $h = shift; my $m = pdl @_; $m->range(ndcoords($m($w - 1:, $h - 1:), [$w, $h])->reorder(2, 3, +0, 1) ->clump(2)->sumover; }



In reply to Re: Fast sliding submatrix sums with PDL (inspired by PWC 248 task 2) by jo37
in thread Fast sliding submatrix sums with PDL (inspired by PWC 248 task 2) by Anonymous Monk

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