Find unique rows (including rows with reverse x,y) in matrix of x,y coordinates

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Peyman Obeidy 2018-9-25

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https://ww2.mathworks.cn/matlabcentral/answers/420627-find-unique-rows-including-rows-with-reverse-x-y-in-matrix-of-x-y-coordinates

评论： Peyman Obeidy 2018-9-25

采纳的回答： Bruno Luong

在 MATLAB Online 中打开

Hi, I would appreciate your comments on this problem.

I would like to extract unique coordinates for example if x=1, y=2, then this point is similar to y=2,x=1 and only one pair is kept.

I have tried two approaches; A) using unique comments

[uniqueA M2 M3] = unique(data(:,[1:2]),'rows'); This found no unique row

b) a for loop which I couldn't complete

for j=1:358
    clear row3
[row1,col1,v1]=find(data(j,1));
[row2,col2,v2]=find(data(j,2));
[row3,col3,v3]=find(data(:,2)==v1 & Tab_Vn_values2(:,1)==v2);
Tab_Vn_valuesTest(j,:)=Tab_Vn_values2(row3,:);
end

Thank you for your time

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Peyman Obeidy 2018-9-25

I think it is only looking at x1=x2 and y1=y2. Is this right?

Peyman Obeidy 2018-9-25

Thank you KSSV for always being helpful too.

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采纳的回答

Bruno Luong 2018-9-25

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/420627-find-unique-rows-including-rows-with-reverse-x-y-in-matrix-of-x-y-coordinates#answer_338302

编辑：Bruno Luong 2018-9-25

在 MATLAB Online 中打开

Try

[~,i] = unique(sort(data(:,1:2),2),'rows')
data(i,:)

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Bruno Luong 2018-9-25

编辑：Bruno Luong 2018-9-25

nothing mysterious

if you want pair (x1,y1) matches the pair (x2,y2) regardless if you swap x and y (in other word after applying any permutation of 2 elements), meaning that if and only if you sort them they matches in order. Sorting a permuted array will bring them back to a unique state.

Peyman Obeidy 2018-9-25