MATLAB: Calculate mean from daily to monthly values.

averagedailymeanmonthly

Below is the code I have so far. It only spits out year 2014 month 12 mean. I need monthly means for all years. So there should be 84 values.
[y,m,d] = datevec(dn);
  for j = [2008:2014]
          for i= [1:12]
              idx=find(y==j&m==i); 
              meandata1=mean(swh(idx)); 
              meandata(84,:)=[84 meandata1]; 
        end
  end
Thank you in advance

Best Answer

dn=datenum('01-01-2008','dd-mm-yyyy'):datenum('31-12-2014','dd-mm-yyyy')
swh=randi(10,numel(dn),1)
[y,m,d] = datevec(dn);
a=[y' m' d']
[ii,jj,kk]=unique(a(:,1:2),'rows')
out=accumarray(kk,(1:numel(kk))',[],@(x) mean(swh(x)))
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