" " == Herbert L Roitblat <roitblat@hawaii.edu> writes:
> Konrad's solution is MUCH more elegant. > Message ----- From: "Konrad Hinsen" <hinsen@cnrs-orleans.fr> [snip] >> How about this: >> >> b = 0*a b[:-1, :-1] = a[1:, 1:] >> I think it looks cleaner as well. I've managed to create a function (with the help of the tips on this list) which can offset a 2d array in either or both the x and y dimensions. I strongly suspect that someone who *gets* python and numeric slicing better than I, can come up with a cleaner approach. def getindicies(o, l): if o > 0: s1 = o; e1 = l; s2 = 0; e2 = l - o elif o < 0: s1 = 0; e1 = l + o; s2 = -o; e2 = l else: s1 = 0; e1 = l; s2 = 0; e2 = l return s1, e1, s2, e2 # return a 2d array whose dimensions match a with the data offset # controlled by x and y. def offset(a, x, y): sy1, ey1, sy2, ey2 = getindicies(y, a.shape[0]) sx1, ex1, sx2, ex2 = getindicies(x, a.shape[1]) b = zeros(a.shape) b[sy1:ey1,sx1:ex1] = a[sy2:ey2,sx2:ex2] return b a = array(((1, 2, 3), (4, 5, 6), (7, 8, 9))) # no offset print offset(a, 0, 0) # offset by 1 column in x print offset(a, 1, 0) # offset by 1 column (opposite dir) in x print offset(a, -1, 0) # offset by 2 columns in x print offset(a, 2, 0) # offset by 2 columns in y print offset(a, 0, 2) Thanks, Mike Romberg (romberg@fsl.noaa.gov)