Select a random cell from multiple matrices

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Geant Bepi
Geant Bepi on 14 May 2015
Commented: Geant Bepi on 14 May 2015
let's say 3 matrices,
A = 30x20; B = 30x20; C = 30x20;
All three matrices contain NaNs.
I want to select a random value from each row out of ALL three matrices but none of the corresponding values should be a NaN. For e.g., if the random value is A(1,10) then B(1,10) and C(1,10) should not contain a NaN. Also it has to be the same cell number(row,column) for all matrices. If nothing matches moves to the next row.
And then repeat it for each row until the end.
Geant Bepi
Geant Bepi on 14 May 2015
A, B and C matrices contain just random numbers (integers). Nans are just all over.
I expect the random value as the output.

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Answers (1)

Guillaume on 14 May 2015
If you want to go randomly through all the elements of the matrices for which none of the matrices contain a nan, simply use randperm to reorder the linear indices that do not contain NaN in any of your matrices:
validindices = find(~(isnan(A) | isnan(B) | isnan(C))); %linear indices that have no nans in any of the matrices
randindices = validindices(randperm(numel(validindices))) %reorder randomly
If you want subscripts instead of linear indices, just use ind2sub to convert, although you can use the linear indices just fine:
[randrows, randcols] = ind2sub(size(A), randindices);


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