@a-s8h/liblevenshtein/lib/liblevenshtein/util/mutate.js

Various utilities regarding Levenshtein transducers.

// Generated by CoffeeScript 1.7.1

/*
Takes a list of arity-1, mutation functions and their corresponding
probabilities, the maximum number of mutations to generate, an arity-0 function
for generating random numbers between 0 and 1, and a target to apply mutations
to, and returns the target, transformed according to a (pseudo-)random series of
mutations.
 */

(function() {
  var global, mutate;

  mutate = function(mutations, max_mutations, random, target) {
    var i, j, mutation, num_mutations, p, p_sum, rand, _i, _len, _ref;
    p_sum = 0;
    for (_i = 0, _len = mutations.length; _i < _len; _i++) {
      _ref = mutations[_i], p = _ref[0], mutation = _ref[1];
      p_sum += p;
    }
    i = -1;
    while ((++i) < mutations.length) {
      mutations[i][0] /= p_sum;
    }
    num_mutations = random() * max_mutations;
    i = -1;
    while ((++i) < num_mutations) {
      rand = random();
      p_sum = 0;
      j = 0;
      while (mutations[j][0] + p_sum < rand) {
        p_sum += mutations[j++][0];
      }
      mutation = mutations[j][1];
      target = mutation(target);
    }
    return target;
  };

  global = typeof exports === 'object' ? exports : typeof window === 'object' ? window : this;

  global['levenshtein'] || (global['levenshtein'] = {});

  global['levenshtein']['mutate'] = mutate;

}).call(this);