Thresholding Matrix Within Cell Array
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Hello,
I have a cell array called output. Each cell within output contains a 1024 x 1024 matrix. I would like to threshold each matrix so that elements below a given value are set to NaN.
I tried using:
output(output < 100000) = NaN;
However, I feel that this is the wrong approach. Intuitively, I want to use a for loop, however, I don't think that will be the most efficient method possible.
Thoughts? Suggestions?
Thanks :)
1 Comment
Image Analyst
on 29 Aug 2017
Why are you using a cell array instead of a regular 3-D array, and why did you want to set it to NaN? What are you going to do with the output array after that?
Accepted Answer
Cam Salzberger
on 29 Aug 2017
Edited: Cam Salzberger
on 31 Aug 2017
cellfun is your friend here. You can create a local, nested, or regular function to do the NaN-setting, and then just apply it to each element of the cell array:
function A = filterMatrix(A,thresh)
A(A < thresh) = NaN;
end
Then call it with:
filteredOutput = cellfun(@(A) filterMatrix(A, 100000), output, 'UniformOutput', false);
-Cam
2 Comments
Cam Salzberger
on 31 Aug 2017
Ah, sorry about that. I forgot you can't do assignment in anonymous functions. Easy enough to make a separate function for it though. I've edited my answer above to function correctly.
Image Analyst has a point though; could you not just create a 3-D matrix originally? That would allow you to do the whole thing in a single call. Also would take less overhead, though it will need a larger contiguous memory chunk.
-Cam
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