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How to get random values from a matrix

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Iftekharuddin Syed
Iftekharuddin Syed 2020-11-10
评论： Bruno Luong 2020-11-10
There is a matrix A (size:12x1000)
How can I select 5 random entries out of 1000( from a matrix of size 12x1000), with each randomly selected value contains all the 12 rows from the original matrix. And store it into another matrix of size 12x5.
Can anyone help me with the code.

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采纳的回答

Ameer Hamza
Ameer Hamza 2020-11-10
You can use randperm() in a for-loop
M = rand(12, 1000);
rand_elements = zeros(12, 5);
for i = 1:12
idx = randperm(1000, 5);
rand_elements(i,:) = M(i, idx);
end

更多回答（2 个）

Stephan
Stephan 2020-11-10
编辑：Stephan 2020-11-10
% Test data to play with
A = rand(12,1000);
% Preallocate
idx = zeros(size(A,1),5);
% 5 unique random indices for every row:
for k = 1:size(A,1)
idx(k,:) = randperm(size(A,2),5);
end
% result
B = A(idx)
Bruno Luong
Bruno Luong 2020-11-10
rcols = randperm(size(A,2),5);
B = A(:,rcols)
  2 个评论
Stephan
Stephan 2020-11-10
I think same indexes for different rows are allowed - arent they?
Bruno Luong
Bruno Luong 2020-11-10
I just interpret the question like this. I don't know if it's what OP wants or not.

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