how to avoid repeat numbers in a row

Dear All,

I have this row

A=[1 2 3 4 5 6];

I tried to find random permutation on the vector but in many cases I got a row with repetition numbers for example

    z=[1 5 2 4 1 5];or z=[1 5 2 4 1 1];

I want to avoid the repetition in this code but it is totally wrong, at first I should assign the missing numbers in such way, here is [3 6].

zc=[3 6 ];
 e=size(zc,2);
   z=[1 5 2 4 1 5];
for i=1:6
    z(i)==z
  s = find((z(i)==z) == 1)
 ss=size(s,2);
 for j=2:ss  
   for   k=1:e
      z(j)=zc(k)
      end
    end
end

I don't want to use a function from matlab to get the permutation, I need to fix my row or any permutation exchange file like (perm file ). If anyone help me for it and save me I will be grateful.

regards,

Imola

[Guillaume]

I don't want to use a function from matlab to get the permutation:

Does that mean that you've written your own uniform number generator? Otherwise, at some point you'll have to use rand, so you just might as well use randperm.

[imola]

yes exactly I used randperm.

Answer 1

[Sean de Wolski]

[~,x] = sort(rand(1,6))

No randperm

[imola]

I m sorry Sean,

 but I wanted to accept Guillaume answer and by mistake I chose yours, how I change it because his answer was great.

regards

Answer 2

[Guillaume]

It seems to me that your effort would be better spent on fixing the code that generate these invalid permutation rather than fixing the permutation afterward.

Anyway, one way to do what you want:

z = [1 5 2 4 1 1];
zc = [3 6];

%build a cell array containing the indices of repeated values:
repindices = accumarray(z', 1:numel(z), [], @(v) {v(2:end)'})'; 
%convert cell array into vector:
repindices = [repindices{:}];
%replace values at indices by replacement:
z(repindices) = zc

[Guillaume]

Note that if you don't randomise which of the duplicates (my code above always pick the first ones) or the order of the replacements, then the distribution of the generated permutations is not uniform

[imola]

Dear Guillaume,

Thank you very much that's was great, I really appreciate that, you save may day, but for zc is there any way to now the repeated numbers in advance, because I will have a lot of rows in my code to change the repetition numbers in them.

Thanks

Imola

[Guillaume]

If you're asking how to build zc:

zc = setdiff(1:6, z)

[imola]

Dear Guillaume,

I'm so sorry, by mistake I chose Sean's answer. Forgave me.

Regards