Perform operation on matrix without for loop
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So I have a 122x64x64 matrix x that has a grid of signals over time. First dim is time, second is x and third is y. Since the signals are all small signals with large DC offsets, I want to remove the offsets from the signals for all time values. The offsets for each signal are stored in a 64x64 matrix.
Here is the code I am currently using:
for a=1:64
for b=1:64
x(:,a,b) = x(:,a,b) - offset(a,b);
end
end
Is there a faster way to do this without a for loop? Later I want to do other similar operations, so a non-loop method would be preferred.
采纳的回答
Roger Stafford
2014-3-19
[m,n] = size(offset);
x = bsxfun(@minus,x,reshape(offset,1,m,n));
更多回答（1 个）
EDIT
permute(bsxfun(@minus,permute(x,[2 3 1]),offset),[3 1 2]);
2 个评论
Shawn
2014-3-19
My bad, forgot about non-singleton dimensions...
x = rand(128,64,64);
offset = rand(64);
tic
your_mat = permute(bsxfun(@minus,permute(x,[2 3 1]),offset),[3 1 2]);
toc
your_mat_1 = x;
for a=1:64
for b=1:64
your_mat_1(:,a,b) = x(:,a,b) - offset(a,b);
end
end
toc
all(your_mat(:) == your_mat_1(:))
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