This question generalizes the previous one Any way for matlab to sum an array according to specified bins NOT by for iteration? Best if there is buildin function for this. I am not sure, but I tried and the answers in previous post seem not to work with matrices.
For example, if
A = [7,8,1,1,2,2,2]; % the bins or subscripts
B = [2,1; ...
1,1; ...
1,1; ...
2,0; ...
3,1; ...
0,2; ...
2,4]; % the matrix
then the desired function "binsum" has two outputs, one is the bins, and the other is the accumulated row vectors. It is adding rows in B according to subscripts in A. For example, for 2, the sum is [3,1] + [0,2] + [2,4] = [5,6], for 1 it is [1,1] + [2,0] = [3,1].
[bins, sums] = binsum(A,B);
bins = [1,2,7,8]
sums = [2,1;
1,1;
3,1;
5,6]
The first method accumarray says its "val" argument can only be a scalar or vector. The second method spare seems not to accept a vector as the value "v" for each tuple (i,j) neither. So I have to post for help again, and it is still not desired to use iterations to go over the columns of B to do this.
I am using 2017a. Many thanks again!