MATLAB: Finding the mean based on a specific value in other column

floating pointlogical indexing

Guys I have following data as an example.The data contain 4 coloumns.want to average 4th coloumn when 1st couloumn is equal to 527.1235 and third coloumn is 927.5

Best Answer

You can find the rows with the first condition and the other rows for the second condition. The intersection of the two rows, are the row numbers that satisfy both conditions:
 rows = intersect(find(a(:,1)==527.1235), find(a(:,3)==927.5));
 % average of the above rows

 avg = mean(a(rows,4));
 disp(avg)
or simpler :
 rows = find(a(:,1)==527.1235 & a(:,3)==927.5);
 % average of the above rows
 avg = mean(a(rows,4));
 disp(avg)
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