Create a vector by selection randomly vectors

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Nikolas Spiliopoulos
Nikolas Spiliopoulos el 5 de Nov. de 2018
Comentada: Nikolas Spiliopoulos el 5 de Nov. de 2018
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.

Respuesta aceptada

Stephan
Stephan el 5 de Nov. de 2018
Editada: Stephan el 5 de Nov. de 2018
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

Más respuestas (2)

Stephen23
Stephen23 el 5 de Nov. de 2018
Editada: Stephen23 el 5 de Nov. de 2018
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

madhan ravi
madhan ravi el 5 de Nov. de 2018
Editada: madhan ravi el 5 de Nov. de 2018
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)
  1 comentario
Stephen23
Stephen23 el 5 de Nov. de 2018
Editada: Stephen23 el 5 de Nov. de 2018
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.

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