Create a vector by selection randomly vectors

Hi all,

I have 4 vectors

A=[1 2 3 4 5];
B=[0 2 5 6 19];
C=[0 0 1 3 0];
D=[1 0 1 15 0];

And I want to create vectors by randomly selecting from the list above, so that I take something like:

Vector1=[B;C;D;A]
Vector2=[C;D;A;B]
Vector3=[A;D;C;B]
.
.
.
etc.

Answer 1

[Stephan]

A=[1 2 3 4 5];
B=[0 2 5 6 19];
C=[0 0 1 3 0];
D=[1 0 1 15 0];
pool = [A; B; C; D];
n = 10 % Number of vectors to create
for k = 1:n
    idx = randperm(4);
    result(k,:) = [pool(idx(1),:), pool(idx(2),:), pool(idx(3),:), pool(idx(4),:)]
end

This code stores the created vectors in the lines of a Matrix. Access them with:

vector_1 = result(1,:)
vector_2 = result(2,:)
.
.
.
vector_n = result(n,:)

Best regards

Stephan

[Nikolas Spiliopoulos]

thanks a lot! it's working..!!

Answer 2

[Stephen23]

Having separate vectors is a pain to work with, so the first thing to do is to put them into one matrix M:

>> M = [1,2,3,4,5;0,2,5,6,19;0,0,1,3,0;1,0,1,15,0]
M =
    1    2    3    4    5
    0    2    5    6   19
    0    0    1    3    0
    1    0    1   15    0
>> N = 7; % how many output matrices
>> [~,R] = sort(rand(N,size(M,1)),2);
>> C = cellfun(@(r)M(r,:),num2cell(R,2),'uni',0);
>> C{:}
ans =
    0    0    1    3    0
    1    0    1   15    0
    0    2    5    6   19
    1    2    3    4    5
ans =
    1    2    3    4    5
    0    2    5    6   19
    1    0    1   15    0
    0    0    1    3    0
ans =
    1    2    3    4    5
    1    0    1   15    0
    0    0    1    3    0
    0    2    5    6   19
ans =
    1    2    3    4    5
    1    0    1   15    0
    0    2    5    6   19
    0    0    1    3    0
ans =
    0    0    1    3    0
    1    0    1   15    0
    1    2    3    4    5
    0    2    5    6   19
ans =
    0    2    5    6   19
    0    0    1    3    0
    1    0    1   15    0
    1    2    3    4    5
ans =
    0    2    5    6   19
    1    0    1   15    0
    1    2    3    4    5
    0    0    1    3    0

Answer 3

[madhan ravi]

EDITED

A=[1 2 3 4 5]; B=[0 2 5 6 19]; C=[0 0 1 3 0]; D=[1 0 1 15 0];
vectors = [A;B;C;D];
n = 10 ;                                      % specify n to create n number of vectors
VECTORS = cell(1,n);                          %PREALLOCATION

for i = 1:n
     VECTORS{i}=[vectors(randsample((1:4),4) ,:)];
end

celldisp(VECTORS)

[Stephen23]

Note that randi can repeat values in its output array, so this answer does not match the examples given (which do not repeat any rows and are all row permutations of the same matrix).

For example:

>> randi([1,4],2,2)
ans =
   1   4
   1   4

Would return A,A,D,D: where are B and C ?

One solution is to use randperm, as Stephan Jung's answer shows.