Finding pair values in a matrix

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Christina Petsa
Christina Petsa 2020-5-31
编辑： the cyclist 2020-5-31
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?
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the cyclist
the cyclist 2020-5-31
编辑：the cyclist 2020-5-31
Can you say exactly what the input is, and exactly what you want the output to be?
Is it just, for example, that if you have a matrix
z = [1 2;
2 1;
3 4;
4 3;
5 6;
6 5];
that you want to return
z2 = [1 2;
3 4;
5 6];
?
It would be helpful if you gave a small, specific example that has enough generality to cover what you want to do.
You can upload data in a MAT file using, the paper-clip icon.
Christina Petsa
Christina Petsa 2020-5-31
That is exactly what I meant. Sorry for not specifying enough!

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回答（2 个）

Tommy
Tommy 2020-5-31
How about this?
z = unique(sort(z,2),'rows');
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Christina Petsa
Christina Petsa 2020-5-31
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 2020-5-31
If my speculation in the comment above about what you want for z2 is correct, then
z2 = unique(sort(z,2),'row')
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Christina Petsa
Christina Petsa 2020-5-31
Hey, I just tried that but the result I get when I type that is two collumns of the same values.
I wanted what you explained above; if z=[3 4; 4 3; 5 2; 2 5] , i want to create a new one that is z2=[3 4; 5 2]
However with this I get a matrix that shows z2=[3 3; 4 4; 5 5;......] etc
Thanks in advance if you have any more ideas...
the cyclist
the cyclist 2020-5-31
编辑：the cyclist 2020-5-31
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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