How to remove duplicate rows in a matrix by considering the repeated values in a specific column?

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%% consider the following example.
A = [1 2 4; 3 5 7;1 5 8; 2 9 4]
In matrix A, column 1 has a duplicate value which is 1. I need to keep the first met value and remove the rest accordingly. At the same time, the indices of non-duplicates should not be changed.
The possible solution should be,
A_without_dup = [1 2 4;3 5 7;2 9 4]
%% only the final row is removed because a duplicate is found in that row based on the value of column 1 in A.
Thanks.

Risposta accettata

Mohammad Sami
Mohammad Sami il 1 Nov 2019
You can use the unique function to return you the index of the unique values in the first column.
Use the stable keyword so the order is preserved. You can then use the index to keep the unique rows.
[~,uidx] = unique(A(:,1),'stable');
A_without_dup = A(uidx,:);
  3 Commenti
David Linsenbardt
David Linsenbardt il 12 Gen 2021
You can also combine rows w/ stable and remove rows where duplicates exist in multiple columns:
[~,uidx] = unique(data(:,[1 2]),'rows','stable');
data = data(uidx,:);

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