循环移位矢量 [英] Circularly shifting a vector

问题描述

我有一个载体，其像

x = [20 11 12 13 14 15 16 17 18 19]

我想转移矢量值给出

I would like to shift the vector values as given

if (i = 1)
X = [11 12 13 14 15 16 17 18 19 20]

if (i = 2)
X = [12 13 14 15 16 17 18 19 20 11]

if (i = 3)
X = [13 14 15 16 17 18 19 20 11 12] 

在present我使用的是为循环来做到这一点，但它需要大量的时间

At present I am using a for loop to do this, but it takes a lot of time

x  = [20 11 12 13 14 15 16 17 18 19];
in = x;
C1 = x;

for lt = 1:1:length(in)
    C1 = x ; 

    if (lt > 1) 
        for tt = 1:1:lt-1
            swap = C1(1);

            for pt = 1:1:length(in)-1
                C1(pt) = C1(pt+1);    
            end   

            C1(length(in)) = swap;
        end
    end    

    disp(C1);
end

能否有人请建议我更快的算法？

Could some one please suggest me a faster algorithm?

推荐答案

让取值表示要移仓的数量。您可以使用 circshift ：

Let s denote the number of positions you want to shift. You can use circshift:

x_shifted = circshift(x, [1 -s]);

第二个参数是 [1 -s] ，因为你要取值位置转移到的左的在第二的维（列）。

The second argument is [1 -s] because you want to shift s positions to the left in the second dimension (columns).

您也可以手动将其与 MOD ：

You can also do it manually with mod:

x_shifted = x(mod((1:numel(x))+s-1, numel(x))+1);

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