# Averaging Every 5 Elements in a Matrix for Each Column with Nans

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Josh on 10 May 2020
Commented: Josh on 11 May 2020
I have a matrix of 2241x6914 and I was hoping to average every 5th element of each column such that the final matrix is 448x6914. The issue is that there are locations in which Nans appear in the data and I dont want these to affect this averaging. Ive tried the below code and it generally works but im curious if there is any way for it to not cause a Nan to default the average of the 5 elements to NaN. What I mean by this is that if the values [1,2,3,Nan,4] were being averaged, the value would return Nan as opposed to the 2.5 I would want. Is there any ways around this? I'll also note that im sure this isnt the most efficient way to code this but it just was the most simple way in my eyes. Any help would be appreciated!
Ch3StrainAvg(1,:)=ChtrainData(1,:);
endCondition=size(Ch3StrainData,1)-4
n=2
for j=2:5:endCondition
Ch3StrainAvg(n,:)=((Ch3StrainData(j,:)+Ch3StrainData(j+1,:)+Ch3StrainData(j+2,:)+Ch3StrainData(j+3,:)+Ch3StrainData(j+4,:))/5);
n=n+1;
end

Toder on 10 May 2020
For x=[1 2 3 NaN 4], like your short example, you can do this to ignore NaNs in the mean:
mean(x(~isnan(x)))
Josh on 11 May 2020
Done!