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Add custom randomFunction option to geneticAlgorithmConstructor #10

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Add custom randomFunction option to geneticAlgorithmConstructor #10

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12 changes: 8 additions & 4 deletions index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,8 @@ module.exports = function geneticAlgorithmConstructor(options) {

doesABeatBFunction : undefined,

randomFunction : function() { return Math.random() },

population : [],
populationSize : 100,
}}
Expand All @@ -23,6 +25,8 @@ module.exports = function geneticAlgorithmConstructor(options) {

settings.doesABeatBFunction = settings.doesABeatBFunction || defaults.doesABeatBFunction

settings.randomFunction = settings.randomFunction || defaults.randomFunction

settings.population = settings.population || defaults.population
if ( settings.population.length <= 0 ) throw Error("population must be an array and contain at least 1 phenotypes")

Expand All @@ -39,7 +43,7 @@ module.exports = function geneticAlgorithmConstructor(options) {
while( settings.population.length < settings.populationSize ) {
settings.population.push(
mutate(
cloneJSON( settings.population[ Math.floor( Math.random() * size ) ] )
cloneJSON( settings.population[ Math.floor( settings.randomFunction() * size ) ] )
)
)
}
Expand All @@ -55,7 +59,7 @@ module.exports = function geneticAlgorithmConstructor(options) {

function crossover(phenotype) {
phenotype = cloneJSON(phenotype)
var mate = settings.population[ Math.floor(Math.random() * settings.population.length ) ]
var mate = settings.population[ Math.floor(settings.randomFunction() * settings.population.length ) ]
mate = cloneJSON(mate)
return settings.crossoverFunction(phenotype,mate)[0]
}
Expand All @@ -78,7 +82,7 @@ module.exports = function geneticAlgorithmConstructor(options) {

nextGeneration.push(phenotype)
if ( doesABeatB( phenotype , competitor )) {
if ( Math.random() < 0.5 ) {
if ( settings.randomFunction() < 0.5 ) {
nextGeneration.push(mutate(phenotype))
} else {
nextGeneration.push(crossover(phenotype))
Expand All @@ -96,7 +100,7 @@ module.exports = function geneticAlgorithmConstructor(options) {
function randomizePopulationOrder( ) {

for( var index = 0 ; index < settings.population.length ; index++ ) {
var otherIndex = Math.floor( Math.random() * settings.population.length )
var otherIndex = Math.floor( settings.randomFunction() * settings.population.length )
var temp = settings.population[otherIndex]
settings.population[otherIndex] = settings.population[index]
settings.population[index] = temp
Expand Down
29 changes: 28 additions & 1 deletion test/basic.js
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Original file line number Diff line number Diff line change
Expand Up @@ -98,6 +98,33 @@ module.exports = {
assert.equal( true , ga.bestScore() > 1 , "Error : untrue : " + ga.bestScore() + " > 1");


}
},
'custom randomFunction works': function (beforeExit, assert) {
let customRandomCalled = false;
const customRandomFunction = () => {
customRandomCalled = true;
return Math.random();
};

var config = {
mutationFunction: function (phenotype) {
return phenotype;
},
crossoverFunction: function (a, b) {
return [a, b];
},
fitnessFunction: function (phenotype) {
return 0;
},
population: [{ name: "alice" }],
randomFunction: customRandomFunction,
};

var geneticalgorithm = geneticAlgorithmConstructor(config);

geneticalgorithm.evolve();
assert.equal(true, customRandomCalled, "customRandomFunction was not called");
},

}