MATLAB: Find nan and eliminate it in matrix

nan in a matrix

hi!
i wann explain may problem with an example:
    % A=[1 2 3;5 4 6;nan nan nan]
to eleminate nan: A=(A(~isnan(A)));
i get this array:A=[1 2 3 5 4  6];
why not A=[1 2 3; 5 4 6]?
i know we could use reshape. is there any other method?
thanx

Best Answer

The reason that a vector rather than a matrix is returned is that MATLAB doesn't know that your "mask" is going to still be rectangular. For example, if your input had been
A = [1 2; 3 NaN];
then your code wouldn't be able to return a matrix.
As Walter's question suggests, you'll need to decide what to do about partial-NaN rows. Probably one of the following is what you want:
% Remove rows with all NaN:
A(all(isnan(A),2),:) = []
% Remove row with any NaN:
A(any(isnan(A),2),:) = []
You could do the analogous operations on columns by changing the 2's to 1's (and using the semicolon in the first index instead of the second).
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