Swap 3 random elements in an array

2018 8 20
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更新时间：2018 8 20
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How do I randomly swap three elements in an array? The element at selected position one will be moved to selected position two, the previous element at selected position two will be moved to position three, and the element at position three will be moved to selected position one.
For example: a=[4 2 3 1 5 7 6] would become anew=[4 2 6 1 3 7 5]
Thank you

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Steven Lord
Steven Lord 2018-8-20

2 个投票

Use randperm to select 3 elements (without replacement) from your vector.
a = [4 2 3 1 5 7 6]
ind = randperm(numel(a), 3)
a(ind) = a(ind([3 1 2]))

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KALYAN ACHARJYA
KALYAN ACHARJYA 2018-8-20
编辑：KALYAN ACHARJYA 2018-8-20

1 个投票

% I have tried this only swap two elements or even numbers, definite swap with each other is only possible in even numbers.
a=randperm(7)
idx=randperm(3);
a(idx)=a(fliplr(idx))
I have tried in another way, you can do that
a=randperm(7)
n=randi(5);
new_array=a(:,:);
new_array([n n+1 n+2])=a([n+2 n n+1])

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Amine Ne
Amine Ne 2018-8-20
Thank you KALYAN, It does not work for example a = [6 7 1 5 2 3 4] becomes [6 7 1 4 2 7 4].
KALYAN ACHARJYA
KALYAN ACHARJYA 2018-8-20
Wait I am doing, there is little an issue.
KALYAN ACHARJYA
KALYAN ACHARJYA 2018-8-20
I have added (Edited answer) another way, pls try, if OK pls confirm it
Amine Ne
Amine Ne 2018-8-20
编辑：Amine Ne 2018-8-20
The second solution allows to swap between 3 consecutive elements.
For example: a=randperm(7)=[7 5 4 1 2 3 6];
n=randi(5)=4; new_array=a(:,:);
new_array([n n+1 n+2])=a([n+2 n n+1])=[7 5 4 3 1 2 6]
I think it is good for me, Thank you KALYAN ACHARJYA for your help and your time.

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