Help me vectorize this code

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VisLab
VisLab 2013-11-7
编辑： Andrei Bobrov 2013-11-8
for x=1:1:rows
for y=1:1:cols
RE_p(y,x) = RE(y,x,bestori_map(y,x));
RO_p(y,x) = RO(y,x,bestori_map(y,x));
end
end
- RE, RO: arrays of size cols*rows*8;
- bestori_map: array of size cols*rows;
what is the best way (and/or fastest) to vectorize this piece of code withouth the need of for cycles ?
Thank you
  2 个评论
Cedric
Cedric 2013-11-7
编辑：Cedric 2013-11-7
What are RE, RO, and bestori_map?
VisLab
VisLab 2013-11-8
编辑：VisLab 2013-11-8
RE, RO - arrays of size cols*rows*8
bestori_map - array of size cols*rows

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采纳的回答

Andrei Bobrov
Andrei Bobrov 2013-11-8
s = size(RE);
[ii,jj] = ndgrid(1:s(1),1:s(2));
ij = sub2ind(s,ii(:),jj(:),bestori_map(:));
RE_p = reshape(RE(ij),s(1:2));
RO_p = reshape(RO(ij),s(1:2));
  1 个评论
VisLab
VisLab 2013-11-8
Works like a charm!
If you'd care to briefly explain the process it would be awesome.
Thank you very much :)

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更多回答（1 个）

Walter Roberson
Walter Roberson 2013-11-7
编辑：Andrei Bobrov 2013-11-8
[X, Y] = ndgrid(1:rows, 1:cols);
X = X(:);
Y = Y(:);
Z = reshape( bestori_map(1:rows,1:cols), [], 1);
linidx = sub2ind(size(RE), X,Y, Z);
RE_p(1:rows,1:cols ) = reshape(RE(linidx),rows, cols );
linidx = sub2ind(size(RO), X, Y, Z);
RO_p(1:rows,1:cols) = reshape(RO(linidx),rows, cols, );
Note: if RE and RO are the same size then you can re-use linidx instead of re-calculating it.
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Andrei Bobrov
Andrei Bobrov 2013-11-8
Hi VisLab! Your RO and RE - functions or arrays?
VisLab
VisLab 2013-11-8
arrays of cols*rows*8 size (RE,RO) and cols*rows (RE_p,RO_p, bestori_map), respectively.

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