MATLAB: How to make a loop to find average of each month

loop monthly average find

I have a data set of monthly averages and would like to make a loop to get an average of every month, so the average of every January, February, and etc.
Here is my data:
1973 1 144.46 4.68
1973 2 118.77 5.05
1973 3 57.76 7.42
1973 4 103.44 6.01
1973 5 84.11 6.18
1973 6 74.74 6.11
1973 7 64.86 6.46
1973 8 69.95 6.07
1973 9 75.25 5.66
1973 10 91.90 5.64
I can do it the hard way:
a=find(vinddata_mean_monthly(:,2)==1);
jan=vinddata_mean_monthly(a,:);
jan_dir=mean(jan(:,3));
jan_spd=mean(jan(:,4));
..
But if anyone could help my make a loop, help would be greatly appreciated.
Kristine

Best Answer

mndata=zeros(12,2);      % preallocate
for m=1:12               % over each month
  mndata(m,:)=mean(vinddata_mean_monthly(vinddata_mean_monthly(:,2)==m,3:4));
end
ADDENDUM
If the data file is regular in not having any missing months, then one can set the row indices directly and eliminate the logical addressing. Unless the size of the data file is humongous it'll likely not be of any real difference, but still...
for m=1:12
  mx(m,:)=mean(vinddata_mean_monthly(m:12:end,3:4));  % take every 12th row
end
Related Question