find nan and eliminate it in matrix
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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
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the cyclist
2012-11-18
编辑:the cyclist
2012-11-19
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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Walter Roberson
2012-11-18
What do you want to have happen if the rows contain unequal number of nans? Do you want to delete the entire row if any member of the row contains a nan? Or only delete the row if it is all nan?
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