Randomly select an element from a vector satisfying a condition
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Dear experts,
I would like to randomly select an element from a vector satisfying a condition. In fact, I want to know what is the fastest way. For example, suppose vector X defined as follows:
X = [1 2 3 4 5 2 3 6 7 8 8 7 9 10 0 1 2 3 8 5 6 4];
How should I randomly select and identify the index of an element in this vector, which is greater than 2?
Thanks for your help,
Amir
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Amirhossein Moosavi
2019-7-1
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Bruno Luong
2019-7-2
The solution seems fine and pretty optimal to me. If you insist on faster move away from MATLAB or buy a faster computer.
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Jos (10584)
2019-7-1
This is a two-step process:
- create an intermediate array with all elements of X satisfying your condition
- select a single element from that
You can combine the two steps in a single command:
randsample(X(X>2), 1)
David Goodmanson
2019-7-2
Relative speeds are going to depend on the length of X and the value N that the elements have to be greater than, (2 in the example). The following is generally faster, by a factor of 2 or so.
f = find(X > M); % M = 2
Ind = f(randi(length(f)));
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