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/**
* The following example generates a population of genes represented by arrays
* of 0's and 1's. The fitness is calculated by the number of 1 bits. The
* mutation function will randomly flip bits.
*/
var _ = require('lodash')
var moment = require('moment')
/*
* =============================================================================
* Import
*/
var Yagal = require('yagal')
const SELECT = Yagal.SELECT
// or
// import Yagal from 'yagal'
// import SELECT from 'yagal/select'
/*
* =============================================================================
* Setup the Genetic Algorithm
*/
const algo = new Yagal({
// Make sure that it does not run for ever
maxGenerations: 100,
// fitness is the number of 1's in the gene. Simple as counting them.
fitFunc: gene => _.sum(gene),
mutation: {
probability: 0.2,
select: SELECT.Tournament2,
evolve: (gene, r) =>
gene.map(bit => {
// if the bit is alread on, low probability of turning it off
if (bit === 1) {
return Math.drand() < 0.1 ? 0 : 1
}
// if the bit is off, then some chance of turning it on
return Math.drand() < 0.35 ? 1 : 0
}),
},
})
/*
* =============================================================================
* Create the initial population for the simulation
*/
// in this example a gene is just going to be an array of 1's and 0's
function randomGene(length) {
return _.range(length).map(() => Math.drandInt(0, 2))
}
// create 100 random genes
const initialPopulation = _.range(100).map(() => randomGene(10))
/*
* =============================================================================
* Run the configured GA against the initial population
*/
const results = algo.run(initialPopulation)
/*
* =============================================================================
* Check the results
*/
console.log(`Started: ${moment(results.startTime).format('lll')}`)
console.log(`Duration: ${results.duration}ms`)
const finalPopulation = results.enrichedPopulation
const fitnessSummary = finalPopulation.fitness
console.log(`Max Fitness: ${fitnessSummary.max}`)
// Hurray, it evolved! Out max fitness is 10, which means that at least 1 gene consists of all 1's.
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