removing matrix element based on quality flag

i have a Netcdf file which includes 150*32024 density matrix and also 150*32024 quality flag matrix (elements of quality flag consist of numbers 1,2,3, ...), that shows the quality of density matrix elements. i want to exclude(replace it by NaN) elements of density matrix related to the quality flag elements equal or greater than 2, how can i do this? Thanks

Answer 1

[Image Analyst]

Try this, using logical indexing:

densityMatrix(qualityMatrix >= 2) = nan;