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Find unique in matrix of x,y coordinates

Asked by Ruchi Bhatia on 19 Dec 2017
Latest activity Commented on by Ruchi Bhatia on 20 Dec 2017
Hello, I would love your help.
If I have a matrix of x,y coordinates for example:
x y
A=[ 2.5 3.5
1.2 3.5
2.2 1.2
1.2 3.5
4.0 2.2 ]
How do I find a unique of this? In the above example one instance of x,y (1.2, 3.5) will be removed?

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3 Answers

Answer by Kelly Kearney
on 19 Dec 2017
 Accepted Answer

To find unique rows, you can use unique with the 'rows' option. (The 'stable' option preserves the input order, if that's important for your application).
unique(A, 'rows', 'stable')

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Thanks. Wow, didn't realize it was that straight forward.

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Answer by Image Analyst
on 19 Dec 2017

Try unique() with the 'rows' option:
uniqueRowsOfA = unique(A, 'rows')

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Did you try this?
[C,IA] = unique(A,'rows');
C contains all unique rows of A. IA contains the indices of the rows of A that are in C. So if you want the indices of the rows that were removed, you can use:
[nrows,~] = size(A);
notIA = setdiff(1:nrows,IA); % duplicate rows

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Thank you! Very helpful.

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