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How to group by in matlab?

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chen xie
chen xie on 8 May 2021
Edited: Cris LaPierre on 8 May 2021
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 Comment
chen xie
chen xie on 8 May 2021
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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Answers (1)

Cris LaPierre
Cris LaPierre on 8 May 2021
Edited: Cris LaPierre on 8 May 2021
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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