Delete rows with the same data in the matrix

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Chenglin Li 2022-11-5

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https://ww2.mathworks.cn/matlabcentral/answers/1844093-delete-rows-with-the-same-data-in-the-matrix

评论： Chenglin Li 2022-11-8

Let's say I have a matrix, and I want to get rid of the duplicates and keep them once, so I can use unique, but I want to get rid of the rows that have the same data but are in different positions and keep them once, so what do I do?

The starting matrix = [1 1;1 2;2 3;4 5;1 1;2 1;3 2];

I want the result = [1 1;1 2;2 3;4 5]; or [1 1;2 1;3 2;4 5];

Can anyone help me with this as I'm completely new with MATLAB. I would be grateful.

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采纳的回答

Jan 2022-11-5

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https://ww2.mathworks.cn/matlabcentral/answers/1844093-delete-rows-with-the-same-data-in-the-matrix#answer_1091958

编辑：Jan 2022-11-6

在 MATLAB Online 中打开

x  = [1  1;2 1;2  3;4  5;1  1;1 2;3  2];  % Swapped [1,2] and [2,1]
sx = sort(x, 2);  % Sort the rows:
[ux, ix] = unique(sx, 'rows', 'stable');
% Solution 1: sorted order
ux
ux = 4×2
     1     1
     1     2
     2     3
     4     5
% Solution 2: original order
x(ix, :)
ans = 4×2
     1     1
     2     1
     2     3
     4     5

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Jan 2022-11-8

Unfortunately the formerly accepted answer was deleted. Its runtime grows quadratically with the size of the input. Although the code I've suggested is faster, it was valuable to see the different approaches to learn for own implementations.

Chenglin Li 2022-11-8