How to group by in matlab?

There is a matrix: [1 3 1;1 3 2;1 3 3;1 3 4;3 1 2;3 1 3]

i want to group by first two columns, and sum the third column.

idealy result is [1 3 10;3 1 5]

[chen xie]

The first two columns of matrix are considered indexes. This is only an example, my dataset is very large and don't know which indexes are duplicated，I want to sum the third column with repeated indexes to form the final matrix.

Answer 1

[Cris LaPierre]

Perhaps with groupsummary?

A=[1 3 1;1 3 2;1 3 3;1 3 4;3 1 2;3 1 3];
[B,BG]=groupsummary(A(:,3),{A(:,1),A(:,2)},'sum');
C = [cell2mat(BG),B]

C = 2×3

1 3 10 3 1 5