Create all unique combination with a vector array

Hello,

let`s say I have a vector a=[1 1 0 0 0]. I want to build all possible combinations with the values within that vector. I`m looking for such result:

[1 0 1 0 0]

[1 0 0 1 0]

[1 0 0 0 1]

[0 1 1 0 0]

[0 1 0 1 0]

and so on till [ 0 0 0 1 1]

With the function perms there is quite a lot of redundancy and the order of the sigles arrays is not the one I would like

[madhan ravi]

What do you mean mean by lots of redundancies, you are the ones asking for unique combinations?

[cht]

If I use perms, they are a lot of combination that are the same. This is the meaning of redundancy.

Answer 1

[Bruno Luong]

Try this, no redundancy created. However the number of combinations still grow very quick so be awared. Where as it gives the order you expect, who knows since you never specify the order you want.

function c = vperm(v)
[u,~,J] = unique(v);
n = accumarray(J(:),1);
c = vpengine(u,n).';
end

function c = vpengine(u,n)
if length(u)==1
    c = u + zeros(n,1);
else
    k = n(1);
    i = nchoosek(1:sum(n),k);
    p = size(i,1);
    j = repmat((1:p)',1,k);
    c = accumarray([i(:),j(:)],1);
    d = vpengine(u(2:end),n(2:end));
    c = repelem(c,1,size(d,2));
    b = c==0;
    d = repmat(d,1,p);
    c(b) = d(:);
    c(~b) = u(1);
end
end

Test:

>> vperm([1 1 0 0 0])

ans =

     0     0     0     1     1
     0     0     1     0     1
     0     0     1     1     0
     0     1     0     0     1
     0     1     0     1     0
     0     1     1     0     0
     1     0     0     0     1
     1     0     0     1     0
     1     0     1     0     0
     1     1     0     0     0

[Bas van Dorp]

Nice work!

I first used unique(perms(a),'rows'). For my purposes that does the same, but it gets very slow and runs out of memory when a is too long. This was limiting my program but with your script it works!

Thanks for this.