Pick a number from an array with a certain probability

2020 5 25
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Hi!
I have an array from 1 to 150 [1 2 3 ...]
and the corresponding probability [0.001 0.003 0.002 ...]
Now I'd like to pick a random number from the first array with taking into account the respective probability.
Has anyone an idea how to proceed?
Thanks!

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Ameer Hamza
Ameer Hamza 2020-5-25
编辑：Ameer Hamza 2020-5-25

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If you can use pre-defined functions and you have Statistics and Machine Learning Toolbox, then you can use randsample(): https://www.mathworks.com/help/releases/R2020a/stats/randsample.html. Something like this
pop = 1:150;
prob = % probability values 1x150
y = randsample(pop, 1000, true, prob)
If you don't have the toolbox, then try following FEX packages:
https://www.mathworks.com/matlabcentral/fileexchange/26003-random-numbers-from-a-user-defined-distribution
https://ww2.mathworks.cn/matlabcentral/fileexchange/14469-performing-random-numbers-generator-from-a-generic-discrete-distribution

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Image Analyst
Image Analyst 2020-5-25

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Is this homework? Sounds like it. See Wikipedia: https://en.wikipedia.org/wiki/Inverse_transform_sampling
Hint: use cumsum(probabililtyVector) and see if a random number is less than the cdf.

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S. B.
S. B. 2020-5-25
No, it's part of my thesis, and I'm working the first time with matlab, that's why it might sounded like a homework.
I've tried it with cumsum already, and with
V (v>=0 & v<0.0027)=0;
V(v>=0.0027 & v<0.0040)=1;
V(v>=0.0040 & v<0.0047)=2;...
but for so many probabilities it is too much work, especially if the probabilities might change again.
But thanks, anyway!

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