How do I make a vector into a loop?

Question

Laura 2013-2-6

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https://ww2.mathworks.cn/matlabcentral/answers/62491-how-do-i-make-a-vector-into-a-loop

for example I need to make the last element (N) in my vector such that (N+1) will correspond to the first element in the vector?

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Azzi Abdelmalek 2013-2-6

Can you give a short example: if x=[1 2 3 4], what should be the result?

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Answer 1

Dan K 2013-2-6

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编辑：Dan K 2013-2-6

在 MATLAB Online 中打开

I think I understand... Are you saying that if you have a five element vector A(1:5), then you want A(6) to actually reference A(1)?

One way I can see to do this is to create a custom index function as an anonymous function. This is a way of doing it for reading only.

>> A = 1:5
A =
     1     2     3     4     5
>> B = @(A,ind)A(mod(ind,length(A)))
B = 
    @(A,ind)A(mod(ind,length(A)))
>> B(A,2)
ans =
     2
>> B(A,7)
ans =
     2
>> B(A,8)
ans =
     3

Here's a quick way of doing it for writing:

    >> A = 1:5;
    >> realind = @(x)mod(x,length(A));
    >> A(realind(27))
    ans =
         2
    >> A(realind(27)) = 5
    A =
         1     5     3     4     5
    >>