Find non zero values in a 4-D array

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Andrew
Andrew 2014-9-23
回答： Adam 2014-9-23
I have a 4D array and I'd like to figure out when under this specific variable are the values non zero.
example:
Array(:,:,:,i) where i goes from 1:6. I need to figure out when the values are non zero and then extract the value of i to be assigned to another variable.
I attempted to work with any(), but I'm having difficulty with that loop.
Example loop:
for i=1:6
if any(Array(:,:,:,i)) = 1
p = i
end
end

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回答（2 个）

Image Analyst
Image Analyst 2014-9-23
Get the logical indices where it's non-zero like this
logicalIndices = Array ~= 0;
I'm not sure what your plans were for that loop you wrote. You're not checking if it's non-zero, you're just checking if each 3D volume has a 1 anywhere it and then setting p equal to the volume index you're checking, but possibly overwriting it on each iteration. Does not make sense to me.
Adam
Adam 2014-9-23
[x,y,z,w] = ind2sub( size(array), find( ~array ) );
will give you 4-d indices of the zero elements if that helps. All the w indices in that result would be the i's you seem to want and the x,y,z at corresponding indices will give the locations in those dimensions if you also need those.

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