How to delete repeated rows without using unique function?

I am looking for a way to delete repeated rows without using the unique function. For example if I have the matrix
A=[2 4 8; 8 2 4; 3 3 -6]
one of the first two rows needs to be deleted. Order doesn't need to be kept. I'm sure I need to use sort, and maybe find or diff. I'm not exactly sure how to go about it.
Any and all help is appreciated!

4 个评论

Why don't you want to use the unique function? It's second output is gonna be real helpful.
Guessing this is homework. That's the usual motivator for not wanting to use particular functions.
It's strange that you consider the first two rows of A to be "repeated", since the order of the elements is different (one is a permutation of the other). Is this what you want?
They are considered repeated because order isn't important here. This is a very small part for my project, and isn't required. My professor said if we could do this we could get some extra credit. Thanks!

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回答(1 个)

Hint:
>> sortrows(sort(A,2))
ans =
-6 3 3
2 4 8
2 4 8
You should now find diff() rather helpful.

2 个评论

I'm still kind of lost where I go from there. Using diff will give me the difference between each element in each row. So when there are three zeros, I know there is a duplicate row. How do I translate that into eliminating a row? I tried using find, but I'm not too familiar with the find function. Thanks for your help.
Lookup ALL and ANY in the doc; you could probably use them at some point, and be aware that ALL, ANY, DIFF, and many others operate along a dimension that you can specify.

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2013-4-23

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