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

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.

x       y
1  2
2  1
2  3
3  2

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

[KSSV]

Why you think unique did not work?

[Peyman Obeidy]

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

[Peyman Obeidy]

Thank you KSSV for always being helpful too.

Answer 1

[Bruno Luong]

Try

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

[Peyman Obeidy]

Thank you, it worked. Would you explain plz

[Bruno Luong]

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]

Thank you, great