[Numpy-discussion] Neighbour-frequency matrix
David Warde-Farley
dwf@cs.toronto....
Wed Jul 15 16:51:01 CDT 2009
Here's an interesting problem, and it might've already been solved by
some of you folks that do image processing:
Suppose I have an 8-bit integer 2-d array, X, and I want a 256x256
matrix that tells me how many times a pixel value v was horizontally
(along second dimension) adjacent to a pixel value b.
So, in an array [[1, 2, 1],[1,1,2],[1,0,0]] the upper left 3x3 square
would be [[1, 1, 0], [1, 1, 3], [0, 3, 0]] with the rest of the matrix
0.
Is there an efficient way to do such a thing with numpy operations? I
can't think of a way.
David
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