How to calculate the mean excluding zero voxels

Hi,

I have a mask with different regions marked with values 1,2,3 and 4. The background is zero.

My data have some NaNs so I set those to 0. I then calculated the mean of my regions but in some cases there were NaNs and now are zero. I want to exclude these voxels from my calculation. My code is the following:

blood(isnan(blood))=0;
bloodmean = accumarray(double(mask(:))+1, blood(:), [], @mean)

Can someone help me to exclude the zero voxels from my calculation?

Answer 1

[Walter Roberson]

Leave the nans as nan, and then

bloodmean = accumarray(double(mask(:))+1, blood(:), [], @nanmean, 0);