How to group by in matlab?

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chen xie
chen xie 2021-5-8
编辑： Cris LaPierre 2021-5-8
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]
  1 个评论
chen xie
chen xie 2021-5-8
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.

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回答（1 个）

Cris LaPierre
Cris LaPierre 2021-5-8
编辑：Cris LaPierre 2021-5-8
Ran in:
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

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