How to sort the elements of a matrix in a random order

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Chimezie Umezie
Chimezie Umezie 2012-8-28
I have three matrix
A=[4,5,8,1,6,3]', B =[1,2,3,7,9,6]' and C=[3,1,2,4,7,9]'
and I want to generate X=[A B C] such that each element in A,B,C is randomly placed. I amusing Matlab 2007b

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Sean de Wolski
Sean de Wolski 2012-8-28
编辑：Sean de Wolski 2012-8-28
So you want each column to be sorted randomly but to still be in the column it came from?
A=[4,5,8,1,6,3]';
B=[1,2,3,7,9,6]';
C=[3,1,2,4,7,9]';
ABC = [A B C]; %concatenate
[~,idx] = sort(rand(size(ABC))); %random indexes
ABCrand = ABC(bsxfun(@plus,idx,0:size(ABC,1):(numel(ABC)-1))) %keep columns aligned
If you don't care about elements staying in their columns, just use randperm. Of course you could always use a for-loop with randperm above, but I won't miss any opportunity to insert a bsxfun somewhere :)
  2 个评论
Chimezie Umezie
Chimezie Umezie 2012-8-28
编辑：Chimezie Umezie 2012-8-28
I am getting the following error message: ??? [~,idx] = sort(rand(size(ABC))) | Error: Expression or statement is incorrect--possibly unbalanced (, {, or [.
I am using Matlab 7.5.0
Sean de Wolski
Sean de Wolski 2012-8-28
If you are on 2007b then you probably need a junk value instead of a '~'
[junk,idx] = sort(rand(size(ABC))); %random indexes

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更多回答（3 个）

Matlabbey
Matlabbey 2012-8-28
maybe you could try making a new random matrix and sorting by those values.
Azzi Abdelmalek
Azzi Abdelmalek 2012-8-28
编辑：Azzi Abdelmalek 2012-8-28
A=[4,5,8,1,6,3]', B =[1,2,3,7,9,6]', C=[3,1,2,4,7,9]'
nA=length(A);
a1=perms(1:nA);nA1=size(a1,1);
res=[A(a1(round(nA1*rand(1,1)),:)); B(a1(round(nA1*rand(1,1)),:)); C(a1(round(nA1*rand(1,1)),:))]
  2 个评论
Chimezie Umezie
Chimezie Umezie 2012-8-28
编辑：Chimezie Umezie 2012-8-28
I am getting the following error message when I used your solution:
"??? Undefined function or method 'randi' for input arguments of type 'double'." My Matlab version is 7.5.0

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Andrei Bobrov
Andrei Bobrov 2012-8-28
abc = [A,B,C]
[~,idx] = sort(rand(size(abc)))
out = abc(sub2ind(size(abc),idx,ones(size(abc,1),1)*(1:size(abc,2))));

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