unique function in matlab

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zhang
zhang 2012-7-31
评论： Walter Roberson 2017-1-21
Hi guys
In the version of R2012a, the unique function has a 'stable' property. Please see the link:
http://www.mathworks.com/help/techdoc/ref/unique.html
A = [9 2 9 5]; [C, ia, ic] = unique(A,'stable')
C =
9 2 5
ia =
1
2
4
ic =
1
2
1
3
But my matlab version is R2010a, it seems that the unique function in R2010a does not support 'stable'. How can I get the stable result?
Thanks,
  4 个评论
显示 2更早的评论
Guillaume
Guillaume 2017-1-21
It's hardly pointless, and it was the addition of a new option to an existing function which is perfectly fine.
Code written for R2010a unique works exactly the same in R2012a
Walter Roberson
Walter Roberson 2017-1-21
Paul Cisek: how would you envision that working? You seem to be implying that Mathworks should only make bug fixes and performance improvements that do not change the output at all (even at the round-off level.) Does that sound like a route to financial viability?

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回答（2 个）

Albert Yam
Albert Yam 2012-7-31
I needed this as well, for R2007a
[uA a b] = unique(A,'first');
C = A(sort(a));
Sean de Wolski
Sean de Wolski 2012-7-31
The 'stable' option was introduced in R2012a.
One way to achieve something similar with an older release is to first sort the vector, then unique it and then index back into the original.
A = [9 2 9 5 5 4 4 1 1 1];
[As,idx] = sort(A);
[U,ij] = unique(As,'first');
A(sort(idx(ij)))

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