Delete rows with the same data in the matrix

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.

Answer 1

[Jan]

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

[Rik]

@Chenglin Li Flags are meant to attract attention from site admins.

I see this answer has already received an upvote. If you want to express your gratitude beyond that, you should post a comment instead of a flag.

[Chenglin Li]

Sorry, I don't know the meaning of Flags in mathwork, but thank you very much for your answer which helped me a lot.

[Bruno Luong]

Jan's answer is clearly better than the accepted answer

[Chenglin Li]

ok！！！

[Jan]

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]

Yes, I thought of using the unique function before, but I didn't sort it.Thank you very much