how to select a random number from the existing matrix in each column

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PRANAY DISHAN 2018-2-7

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https://ww2.mathworks.cn/matlabcentral/answers/381232-how-to-select-a-random-number-from-the-existing-matrix-in-each-column

评论： PRANAY DISHAN 2018-2-7

Dear friends, I need to select a random number from each column from the existing matrix to create a new row as shown below: I'm new to matlab. So please help me with this. Thank you.

A=[1 2 3 4;5 6 7 8;9 10 11 12]

Anew=[5 2 7 12]

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Answer 1

Roger Stafford 2018-2-7

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https://ww2.mathworks.cn/matlabcentral/answers/381232-how-to-select-a-random-number-from-the-existing-matrix-in-each-column#answer_303833

编辑：Roger Stafford 2018-2-7

在 MATLAB Online 中打开

[m,n] = size(A);
Anew = A(randi(m,[1,n])+m*(0:n-1));

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Answer 2

per isakson 2018-2-7

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https://ww2.mathworks.cn/matlabcentral/answers/381232-how-to-select-a-random-number-from-the-existing-matrix-in-each-column#answer_303834

编辑：per isakson 2018-2-7

在 MATLAB Online 中打开

It's smarter to use a for-loop

>> A
A =
     1     2     3     4
     5     6     7     8
     9    10    11    12
>> [nrow,ncol] = size(A);
>> ix = randi([1,nrow],[1,ncol])
ix =
     3     1     3     1
>> A(sub2ind(size(A),ix,1:ncol))
ans =
     9     2    11     4