I’m not a MATLAB expert myself, but I had to code the roulette wheel selection algorithm, once again, this time in the MATLAB programming language. It complements this post, so I thought I could share it:

% ---------------------------------------------------------
% Roulette Wheel Selection Algorithm. A set of weights
% represents the probability of selection of each
% individual in a group of choices. It returns the index
% of the chosen individual.
% Usage example:
% fortune_wheel ([1 5 3 15 8 1])
%    most probable result is 4 (weights 15)
% ---------------------------------------------------------
function choice = fortune_wheel(weights)
  accumulation = cumsum(weights);
  p = rand() * accumulation(end);
  chosen_index = -1;
  for index = 1 : length(accumulation)
    if (accumulation(index) > p)
      chosen_index = index;
      break;
    end
  end
  choice = chosen_index;

It can be probably rewritten in a nice MATLAB way, but it’s useful as is.