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

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

[Azzi Abdelmalek]

each element in A,B,C is randomly placed before or after concatenation?

[Chimezie Umezie]

before concatenation. Thanks

Answer 1

[Sean de Wolski]

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 :)

[Chimezie Umezie]

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]

If you are on 2007b then you probably need a junk value instead of a '~'

[junk,idx] = sort(rand(size(ABC))); %random indexes

Answer 2

[Matlabbey]

maybe you could try making a new random matrix and sorting by those values.

Answer 3

[Azzi Abdelmalek]

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)),:))]

[Chimezie Umezie]

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

[Azzi Abdelmalek]

replace randi with round(nA1*rand(1,1))

Answer 4

[Andrei Bobrov]

abc = [A,B,C]
[~,idx] = sort(rand(size(abc)))
out = abc(sub2ind(size(abc),idx,ones(size(abc,1),1)*(1:size(abc,2))));