MATLAB: Perplexed by logical condition result

logical indexing

I have a matrix that is a mixture of numbers and NaNs by construction. I looking through answers as to how to use functions like GEOMEAN and MEAN on these type of matrices while ignoring the NaNs in these calculations. I found a response indicating I could use the following structure:
condition=isnan(A)
B=geomean(A(~condition))
The "condition" assignment statement works like a charm. In my case it creates an 87×181 logical matrix which is the same dimension as A. However, the statement "A(~condition)" creates a column vector that stacks all my numerical data from A on top of each other instead of preserving the 87×181 structure. This of course completely screws up the GEOMEAN calculation since it returns a single number instead of 181 different numbers.
Appreciate any help,
JK

Best Answer

If you have geomean, you have the Statistics Toolbox. If you want to take the geometric mean of your array (with NaN values included, use nanmean of the logs of the values:
A = randi(10, 15, 20);
A(A == 5) = NaN;
B = exp(nanmean(log(A)));
A bit indirect, but it gets you the result you want, with the dimensions you want.
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