问题描述:

I was wondering if there was a way to generate all possible permutations for 2 vectors. I know that I can use perms, but that just works for one vector.

What I would like is to input the vector [1 2 3]

and would get out

`V1 = [] V2 = [1 2 3]`

V1 = [1 2 3] V2 = []

V1 = [1] V2 = [2 3]

V1 = [2] V2 = [1 3]

...

Also could I store all of these permutations in a cell array becuase they all have different lengths so a Matrix won't work.

Is this what you want?

```
output = {};
v = [1 2 3]; % input
N = length(v);
for k=1:2^N
m = logical( bitget(k, 1:N) ); % mask selecting elements of v1
v1 = v(m);
v2 = v(~m);
output{end+1} = {v1, v2};
end
```

In almost one line, the credit should go to seb though.

```
v = [1 2 3 4];
N = numel(v);
out = cellfun(@(x) {v(x) v(~x)}, mat2cell( logical( bsxfun(@bitget,(1:2^N)', (1:N)) ) ,ones(1,2^N),N) , 'uni', 0)
```

My old answer, clumsy, but works:

```
A = arrayfun(@(x) nchoosek(V,x), 1:numel(V), 'uni',0);
B = cellfun(@(x) mat2cell(x,ones(1,size(x,1)),size(x,2)),A,'uni',0);
V1 = vertcat({[]},B{:});
V2 = cellfun(@(x) setdiff(V,x), V1, 'uni',0);
```

gives:

```
>> celldisp(V1)
V1{1} =
[]
V1{2} =
1
V1{3} =
2
V1{4} =
3
V1{5} =
1 2
V1{6} =
1 3
V1{7} =
2 3
V1{8} =
1 2 3
```

and for `V2`

right the opposite.

Try the following solution:

```
a=num2cell(1:3);
output1=cellfun(@(x) nchoosek(1:3,x),a,'UniformOutput',false);
output_reverse=cellfun(@(x) nchoosek(3:-1:1,x),a(2:3),'UniformOutput',false);
```

For a sequence of `1,2,3`

, the output would be as follows:

```
output1{1}=
1
2
3
output1{2}=
1 2
1 3
2 3
output1{3}=
1 2 3
```

Execute the `output_reverse`

line only when you require the reverse combinations also. Hope this is what you are looking for.

Use a loop over all possible divisions. For each division, compute a mask (logical index) that tells which elements go to `V1`

and which go to `V2`

. The following assumes order is not important, i.e. `[1],[2 3]`

is the same division as `[1], [3 2]`

.

```
vector = [1 2 3]; %// example data
N = numel(vector); %// number of elements
NN = 2^N; %// number of results
V1 = cell(1,NN); %// intiallize
V2 = cell(1,NN); %// intiallize
for n = 0:NN-1;
mask = logical(dec2bin(n,N)-'0'); %// logical index for values in V1
V1{n+1} = vector(mask);
V2{n+1} = vector(~mask);
end
```

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