I know how to generate random numbers in a certain range in Matlab. What i am trying to do now is generate random numbers in a range where there is more chance of getting certain ones.
For example: how could i use Matlab to generate random numbers between 0 and 2, where 50% of them will be less than 0.5?
To get numbers between 0 and 2 I would use (2-0)*rand+0. How can i do this but get a certain percentage of the numbers generated to be less than 0.5? Is there a way to do this using the rand function?
Here is a suggestion:
N = 10; % how many random numbers to generate
bounds = [0 0.5 1 2]; % define the ranges
prob = cumsum([0.5 0.3 0.2]); % define the probabilities
% pick a random range with probability from prob :
s = size(bounds,2)-cumsum(bsxfun(@lt,rand(N,1),prob),2);
% pick a random number in this range:
b = rand(1,N).*(bounds(s(:,end)+1)-bounds(s(:,end)))+bounds(s(:,end))
Here we have a probability of prob(k) to draw a number between bounds(k) to bounds(k+1). Basically we first draw a range with defined probability, and then draw another number from the range. So we are interested only in b, but need s on the way (mainly for creating a lot of numbers in a vectorized manner).
so we get:
b =
Columns 1 through 5
0.5297 0.15791 0.88636 0.34822 0.062666
Columns 6 through 10
0.065076 0.54618 0.0039101 0.21155 0.82779
Or, for N = 100000 we can draw:
https://i.stack.imgur.com/pkFgY.png
https://i.stack.imgur.com/pkFgY.png
so we can see how the values are distributed between the 3 ranges in bounds.
http://stackoverflow.com/questions/40294890/generating-random-numbers-with-weighted-distribution-in-matlab
