How to interchange elements of an array?

Question

Noor Fatima 2022-3-27

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1681929-how-to-interchange-elements-of-an-array

评论： Voss 2022-3-28

采纳的回答： Voss

X = [ 4 2 3 6 5 1]

x1 = [2 3 1 2]

I want to interchange entries of X based on x1, that is

Output X =[4 6 2 3 5 1];

Any help is appreciated.

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Answer 1

Voss 2022-3-27

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1681929-how-to-interchange-elements-of-an-array#answer_928194

在 MATLAB Online 中打开

X = [  4     2     3     6     5     1];
x1 = [2 3 1 2];
Xnew = X;
for ii = 1:numel(x1)
    Xnew([ii x1(ii)]) = Xnew([x1(ii) ii]);
end
Xnew
Xnew = 1×6
     4     6     2     3     5     1

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Noor Fatima 2022-3-28

@_Thank you, Is it possible without loop?

Voss 2022-3-28

在 MATLAB Online 中打开

Well, you can write down an expression to do it in this particular case:

X = [  4     2     3     6     5     1];
Xnew = X([1 4 2 3 5 6])
Xnew = 1×6
     4     6     2     3     5     1

But I don't think you can do it in general without using a loop somewhere, because the result of any swap depends on the results of the previous swaps, so it's necessarily an iterative process.

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