Is it possible to sort an array by making the repeated elements in the last?

1 次查看（过去 30 天）
Mohammad Ayoub
Mohammad Ayoub 2018-2-21
评论： Mohammad Ayoub 2018-2-21
Greetings.
Consider a vector A = [-2 -2 -1 3 3], is it possible to sort this vector (a generalized method) to [-1 -2 -2 -3 -3]?
The only thing that matters is that the repeated elements are in the last, it doesn't matter what way the repeated elements themselves are sorted (for example, [-1 -2 -2 -3 -3] or [-1 -3 -3 -2 -2] are fine) I just want the distinct value to be on the left before any repeated value.
Thank you in advance,
M. Ayoub

请先登录，再回答此问题。

采纳的回答

Stephen23
Stephen23 2018-2-21
编辑：Stephen23 2018-2-21
>> A = [-2,-2,-1,3,3,3,9,9,0,99]
A =
-2 -2 -1 3 3 3 9 9 0 99
>> [cnt,idx] = histc(A,unique(A));
>> [~,idy] = sort(cnt>1);
>> [~,idz] = ismember(idx,idy);
>> [~,ids] = sort(idz);
>> B = A(ids)
B =
-1 0 99 -2 -2 3 3 3 9 9
And
>> A = [-1,-1,-3,-5,-5]
...
B =
-3 -5 -5 -1 -1
  2 个评论
Jan
Jan 2018-2-21
This sorts in unique, twice in sort and again in ismember. In addition the perfectly working histc is deprecated (what a pity!).
Mohammad Ayoub
Mohammad Ayoub 2018-2-21
Thank you Stephen and Jan.
Jan I know your answer is true but I think it is a little advanced for me haha, my code is really small and I am still new to MATLAB, so what Stephen wrote works perfectly fine in my application!
By the way, can anyone explain to me what happened exactly (step by step or write the code again with comments) in the code? If you please, so I can understand it better.
Thank you very much!

请先登录，再进行评论。

更多回答（2 个）

KSSV
KSSV 2018-2-21
A = [-2 -2 -1 3 3] ;
s = sign(A) ;
[val,idx] = sort(abs(A)) ;
iwant = s(idx).*val
  3 个评论
显示 1更早的评论
Mohammad Ayoub
Mohammad Ayoub 2018-2-21
The result I expect is [-3 -1 -1 -5 -5] or [-3 -5 -5 -1 -1]
The important thing is that the -3 (which is not repeated) is in the beginning of the array.
By the way, I am limiting my code to 1 repeated value, there will be no more than one repeated element in the arrays (I think this makes it slightly easier)

请先登录，再进行评论。

Jan
Jan 2018-2-21
编辑：Jan 2018-2-21
With FEX: RunLength:
A = [-1 -1 -3 -5 -5];
[b, n] = RunLength(sort(A));
m = (n == 1);
result = [b(m), RunLength(b(~m), n(~m)];
If you do not have a C-compiler installed, use RunLength_M from this submission.
Maybe this is faster:
sA = sort(A);
[b, n, index] = RunLength(sA);
mask = false(size(A));
mask(index(n == 1)) = true;
result = [sA(mask), sA(~mask)];

类别

在 Help Center 和 File Exchange 中查找有关 Multidimensional Arrays 的更多信息

标签

产品

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by