reordering the data

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kash
kash 2012-2-7
i have values as
D=[1 2 3 4 5 6 7 ]
now i want to reorder the data
D1=[3 4 7 1 2 6 5]this is for example,
i want the order to be changed from D,without using randperm function,please help

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采纳的回答

Andreas Goser
Andreas Goser 2012-2-7
What about generating two random numbers as indices and swapping the data of the indices? And then do this in a loop.
clc
D=[1 2 3 4 5 6 7 ]
for k=1:10
x1=randi(length(D));
x2=randi(length(D));
dummy=D(x1);
D(x1)=D(x2);
D(x2)=dummy
end

更多回答（3 个）

Junaid
Junaid 2012-2-7
Second possible way is
D = [1 2 3 4 5 6 7];
declare any temp variable to have the order of indices. For example.
T = [3 4 7 1 2 6 5];
D1 = D(T);
In given example your indices and values are same, but for different values following code will work.
Jan
Jan 2012-2-7
D.E. Knuth has shown some shuffle methods, e.g.:
D1 = D;
for i = 2:numel(D) % Knuth shuffle in forward direction:
w = ceil(rand * i); % 1 <= w <= i
t = D1(w);
D1(w) = D1(i);
D1(i) = t;
end
This is proven to be unbiased and cheaper than using 2 random numbers for swapping. See also: FEX: RPG-lab.
Sean de Wolski
Sean de Wolski 2012-2-7
Sure:
[~, idx] = sort(rand(size(D)));
D1 = D(idx);

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