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How permutate 2-by-2 matrices in a single matrix

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Peiman Khandar
Peiman Khandar 2022-10-28
编辑： Peiman Khandar 2022-10-29
Hello everyone
I have three matrices as:
a = [1,2;3,4]; b = [2,5;1,6]; c = [3,7;2,4];
and collect them in a single M matrix as, M = [a,b,c]. Now I want to have permutation of these three matrices in M_P matrix as:
M_P = [a b c;
a c b;
b a c;
b c a;
c a b;
c b a].
When I use M_P = perms(M), I could not obtain the [M_P] written above. it permutation all the value inside the matirices, however I just want permutation just matrices (a,b,c) then, place the values of matrices. I would appriciate it you can help me
Thanks in advance

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采纳的回答

Bruno Luong
Bruno Luong 2022-10-28
Ran in:
a = [1,2;3,4]; b = [2,5;1,6]; c = [3,7;2,4];
abc= {a,b,c};
abc=perms(abc)
abc = 6×3 cell array
{2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double}
abc=cell2mat(abc)
abc = 12×6
3 7 2 5 1 2 2 4 1 6 3 4 3 7 1 2 2 5 2 4 3 4 1 6 2 5 3 7 1 2 1 6 2 4 3 4 2 5 1 2 3 7 1 6 3 4 2 4 1 2 3 7 2 5 3 4 2 4 1 6
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Bruno Luong
Bruno Luong 2022-10-29
Take a look at cellfun
It's funny that you ask to create data in format that you don't know how to work with. It is better that you don't jump quickly and think more about the data structure that you know how to manipulate downstream.
Might be what you need is 4D array and not a 2D array of all permulations clump together.
Peiman Khandar
Peiman Khandar 2022-10-29
I see. So in that case are you recommending an otherway to obtain my permutation function cause I need to do mathematical operations on it

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更多回答（1 个）

Rik
Rik 2022-10-28
编辑：Rik 2022-10-28
Ran in:
You're close. You just need to store a, b, and c in a cell array and use perms to create indices.
The benefit of this approach is that you can extend it to more or fewer elements (although you will run into memory constraints fast with a larger number of matrices).
a = [1,2;3,4]; b = [2,5;1,6]; c = [3,7;2,4];
collation = {a,b,c};
inds = perms(1:numel(collation))
inds = 6×3
3 2 1 3 1 2 2 3 1 2 1 3 1 3 2 1 2 3
M_P = collation(inds)
M_P = 6×3 cell array
{2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double} {2×2 double}
M_P = cell2mat(M_P)
M_P = 12×6
3 7 2 5 1 2 2 4 1 6 3 4 3 7 1 2 2 5 2 4 3 4 1 6 2 5 3 7 1 2 1 6 2 4 3 4 2 5 1 2 3 7 1 6 3 4 2 4 1 2 3 7 2 5 3 4 2 4 1 6
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Bruno Luong
Bruno Luong 2022-10-29
Ran in:
a = [1,2;3,4]; b = [2,5;1,6]; c = [3,7;2,4];
abc= {a,b,c};
abc=perms(abc);
2*abc{1,1}
ans = 2×2
6 14 4 8

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