Finding pair values in a matrix

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Christina Petsa
Christina Petsa on 31 May 2020
Edited: the cyclist on 31 May 2020
We had to calculate how many pairs we can find for the pythagorean triads for a,b,c when a^2+b^2=c^2. After we found those we had to create a matrix that included all possible pairs for a and b. For a=[1:100] and b=[1:200] I got 184 pairs. So now my matrix z is a 184x2 matrix, but there are definitely some pairs that are repeated. For example, when c=5 we get two possibilities x=3 and y=4, but also x=4 and y=3.
How can I make the code, so that if i have the rows (3,4) and (4,3), either one will be deleted and I can have a new matrix just for the possible pairs without caring which one is x or y?
I tried doing that with groupcounts(z) but that only works with vectors, not matrices. Any ideas?
  2 Comments
Christina Petsa
Christina Petsa on 31 May 2020
That is exactly what I meant. Sorry for not specifying enough!

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Answers (2)

Tommy
Tommy on 31 May 2020
How about this?
z = unique(sort(z,2),'rows');
  3 Comments
Christina Petsa
Christina Petsa on 31 May 2020
It doesn't work the way we expected. If you don't mind I replied what the output is bellow, if you have any more ideas, I'd be thankful!

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the cyclist
the cyclist on 31 May 2020
If my speculation in the comment above about what you want for z2 is correct, then
z2 = unique(sort(z,2),'row')
  3 Comments
the cyclist
the cyclist on 31 May 2020
Edited: the cyclist on 31 May 2020
Are you absolutely certain you typed the solution code exactly as we wrote it? Because it worked for me.
I'm guessing maybe you wrote
sort(z)
instead of
sort(z,2)
The correct syntax sorts along dimension 2.

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