Random vector non repeated otherwise create new vector

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Yigitalp Ozmen 2019-7-12

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关闭： MATLAB Answer Bot 2021-8-20

Hello,

I have number list from 1 to 5. We know there are 120 different permutation for these. I want to write a rule that for my algorithm, I want to create a permutation that does not creaated before. For example,

1 2 3 4 5 first

2 3 4 5 1 second

...

2 3 4 5 1 nth it shouldn't be created. It is already in the second iteration.

So, by this manner creations should end at most 120th trial.

Can you help me solve this? I'm using randperm

Thank you.

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Guillaume 2019-7-12

randperm doesn't keep track of previously generated permutations, so it's never going to be useful for this.

Why can't you just generate at once the 120 permutations (with perm) and shuffle them if needed?

Stephen23 2019-7-12

Create all permutations, then pick randomly.

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Answer 1

Brendan Hamm 2019-7-12

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https://ww2.mathworks.cn/matlabcentral/answers/471473-random-vector-non-repeated-otherwise-create-new-vector#answer_383020

在 MATLAB Online 中打开

p = perms(1:5);
idx = randi([1,size(p,1)]);
selection = p(idx,:)

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Answer 2

Yigitalp Ozmen 2019-7-12

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/471473-random-vector-non-repeated-otherwise-create-new-vector#answer_383021

Thank you for your answers. What about for bigger numbers such as 10. Matlab cant generate 10!. But maybe it can generate permutations different from previous ones. Is it achivable?