How to take the average of each column of a matrix without including a certain number

I have a matrix that has 864 rows and 7 columns and is filled with positive numbers and zeros. I want to take the average of each of those columns. However when MATLAB is taking the averages, I dont want it to include the zeros in its calculations. Can this be done?

Answer 1

[Joseph Cheng]

What you can do is do a quick substitution. if you know your matrix doesn't have any NaN (Not a number) then substitute the 0's for nan and then use the nanmean() which will exclude the NaNs from the average.

 B=A;
 B(A==0)=nan;
 NonZeroAverages = nanmean(B);

[Hail]

Thanks

Answer 2

[Image Analyst]

If you don't have nanmean because you don't have the Finance or Statistics toolbox, you can simply do

columnMeans = sum(a, 1) ./ sum(a~=0);

where "a" is the name of your matrix. This sums up the values in each column, then divides it by the sum of the non-zero values in each column.

[Image Analyst]

Even if you do have those toolboxes, I'd use this method instead.

Answer 3

[Sara]

Let's call your array "a":

my_mean = zeros(size(a,2),1);
for i = 1:size(a,2)
    d = a(:,i);d = d(d~=0);
    my_mean(i) = mean(d);
end

[Hail]

thanks