You can multiply with accumarray if you specify the prod function as the function you want it to use. This is an adaptation of a recent Answer that wanted to take the mean of values in the second column of the matrix that shared the same value of the first column, so I originally used the mean function. Here, I’m multiplying them instead, using the prod function:
ExCellArray = {[1 3.1; 2 4.5; 3 5.7; 4 8.2; 4 5.2]};
ExArray = cell2mat(ExCellArray);
[UExA, ia, ic] = unique(ExArray(:,1));
Out = [ExArray(ia,1) accumarray(ic, ExArray(:,2), [], @prod)]
Out =
1 3.1
2 4.5
3 5.7
4 42.64
The accumarray function can do a lot of neat stuff if you just ask it nicely!
Best Answer