How to choose a random value from an array?

Question

ozan aksu 2018-6-21

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https://ww2.mathworks.cn/matlabcentral/answers/406794-how-to-choose-a-random-value-from-an-array

评论： ozan aksu 2018-6-23

I have a matrix

    A=  [2846        2402        2374         209
          54          46          45           4
          35          70          35          35
           2           2           2           2
           2           4          10          12]

I want to select a random element among the values which are lower than 50 from the third row, in other words, one of the 35s. I also want to obtain the column number of the value that i have selected. Couldn't find a decent way to do it.

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Answer 1

Stephen23 2018-6-21

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https://ww2.mathworks.cn/matlabcentral/answers/406794-how-to-choose-a-random-value-from-an-array#answer_325679

编辑：Stephen23 2018-6-21

在 MATLAB Online 中打开

>> X = A(3,:)<50; % columns with <50 in third row
>> V = find(X);
>> C = V(randi(nnz(X))) % random column
C =  3
>> A(3,C) % value from that column
ans =  35
>> A(:,C) % the whole column
ans =
   2374
     45
     35
      2
     10