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https://github.com/khezen/evoli

Genetic Algorithm and Particle Swarm Optimization
https://github.com/khezen/evoli

evolutionary-algorithms genetic-algorithm go golang particle-swarm-optimization

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Genetic Algorithm and Particle Swarm Optimization

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README 

        
# *evoli*



[![GoDoc](https://img.shields.io/badge/go-documentation-blue.svg)](https://godoc.org/github.com/khezen/evoli)

[![Build Status](https://github.com/khezen/evoli/workflows/build/badge.svg?branch=master)](https://github.com/khezen/evoli/actions?query=workflow%3Abuild) [![codecov](https://img.shields.io/codecov/c/github/khezen/evoli/master.svg)](https://codecov.io/gh/khezen/evoli)

[![Go Report Card](https://goreportcard.com/badge/github.com/khezen/evoli)](https://goreportcard.com/report/github.com/khezen/evoli)



Genetic Algorithm and Particle Swarm Optimization written in Go



## Example



### Problem



Given `f(x,y) = cos(x^2 * y^2) * 1/(x^2 * y^2 + 1)`



Find `(x,y)` such as `f(x,y)` reaches its maximum 



Answer `f(0,0) = 1`



### Particle Swarm Optimization



```golang

package main



import (

	"fmt"

	"math"

	"math/rand"



	"github.com/khezen/evoli"

)



// 3d cosine that gets smaller as you move away from 0,0

func f(x, y float64) float64 {

	d := x*x + y*y

	return math.Cos(d) * (1 / (d/10 + 1))

}



type FIndividual struct {

	v       []float64

	x       []float64

	fitness float64

}



func (i *FIndividual) Equal(other evoli.Individual) bool {

	return i == other

}



func (i *FIndividual) Fitness() float64 {

	return i.fitness

}



func (i *FIndividual) SetFitness(newFitness float64) {

	i.fitness = newFitness

}



type FPositioner struct {

}



func (p *FPositioner) Position(indiv, pBest, gBest evoli.Individual, c1, c2 float64) (evoli.Individual, error) {

	fIndiv, ok1 := indiv.(*FIndividual)

	fPBest, ok2 := pBest.(*FIndividual)

	fGBest, ok3 := gBest.(*FIndividual)

	if !ok1 || !ok2 || !ok3 {

		return nil, fmt.Errorf("invalid individual type")

	}

	newIndiv := FIndividual{

		v: make([]float64, len(fIndiv.v)),

		x: make([]float64, len(fIndiv.v)),

	}

	w := 0.9

	for d := range fIndiv.v {

		rp := rand.Float64()

		rg := rand.Float64()

		newIndiv.v[d] = w*fIndiv.v[d] +

			c1*rp*(fPBest.x[d]-fIndiv.x[d]) +

			c2*rg*(fGBest.x[d]-fIndiv.x[d])



		newIndiv.x[d] = fIndiv.x[d] + newIndiv.v[d]

	}

	return &newIndiv, nil

}



type FEvaluater struct {

}



func (e *FEvaluater) Evaluate(indiv evoli.Individual) (Fitness float64, err error) {

	fIndiv, ok := indiv.(*FIndividual)

	if !ok {

		return 0, fmt.Errorf("invalid individual type")

	}

	return f(fIndiv.x[0], fIndiv.x[1]), nil

}



func main() {

	pop := evoli.NewPopulation(50)

	for i := 0; i < pop.Cap(); i++ {

		x := rand.Float64()*20 - 10

		y := rand.Float64()*20 - 10

		vx := rand.Float64()*20 - 10

		vy := rand.Float64()*20 - 10

		pop.Add(&FIndividual{

			x: []float64{x, y},

			v: []float64{vx, vy},

		})

	}

	positioner := &FPositioner{}

	evaluator := &FEvaluater{}



	sw := evoli.NewSwarm(pop, positioner, .2, .2, evaluator)



	for i := 0; i < 100; i++ {

		err := sw.Next()

		if err != nil {

			panic(err)

		}

	}



	// evaluate the latest population

	for _, v := range sw.Population().Slice() {

		f, err := evaluator.Evaluate(v)

		if err != nil {

			panic(err)

		}

		v.SetFitness(f)

	}



	fmt.Printf("Max Value: %.2f\n", sw.Alpha().Fitness())

}

```



```bash

Max Value: 1.00

```



### Gentic Algorithm



```golang

package main



import (

	"fmt"

	"math"

	"math/rand"



	"github.com/khezen/evoli"

)



// 3d cosine that gets smaller as you move away from 0,0

func h(x, y float64) float64 {

	d := x*x + y*y

	return math.Cos(d) * (1 / (d/10 + 1))

}



type HIndividual struct {

	v       []float64

	x       []float64

	fitness float64

}



func (i *HIndividual) Equal(other evoli.Individual) bool {

	return i == other

}



func (i *HIndividual) Fitness() float64 {

	return i.fitness

}



func (i *HIndividual) SetFitness(newFitness float64) {

	i.fitness = newFitness

}



type HMutater struct {

}



func (m *HMutater) Mutate(indiv evoli.Individual, mutationProbability float64) (evoli.Individual, error) {

	hIndiv1, ok := indiv.(*HIndividual)

	if !ok {

		return nil, fmt.Errorf("invalid individual type")

	}

	x := hIndiv1.x[0]

	y := hIndiv1.x[1]

	vx := hIndiv1.v[0]

	vy := hIndiv1.v[1]

	if mutationProbability > rand.Float64() {

		x = rand.Float64()*20 - 10

	}

	if mutationProbability > rand.Float64() {

		y = rand.Float64()*20 - 10

	}

	if mutationProbability > rand.Float64() {

		vx = rand.Float64()*20 - 10

	}

	if mutationProbability > rand.Float64() {

		vy = rand.Float64()*20 - 10

	}

	return &HIndividual{

		x: []float64{x, y},

		v: []float64{vx, vy},

	}, nil

}



type HCrosser struct {

}



func (h *HCrosser) Cross(indiv1, indiv2 evoli.Individual) (evoli.Individual, evoli.Individual, error) {

	hIndiv1, ok1 := indiv1.(*HIndividual)

	hIndiv2, ok2 := indiv2.(*HIndividual)

	if !ok1 || !ok2 {

		return nil, nil, fmt.Errorf("invalid individual type")

	}

	return &HIndividual{

			x: []float64{hIndiv1.x[0], hIndiv2.x[1]},

			v: []float64{hIndiv1.v[0], hIndiv2.v[1]},

		}, &HIndividual{

			x: []float64{hIndiv2.x[0], hIndiv1.x[1]},

			v: []float64{hIndiv2.v[0], hIndiv1.v[1]},

		}, nil

}



type HEvaluater struct {

}



func (e *HEvaluater) Evaluate(indiv evoli.Individual) (Fitness float64, err error) {

	fIndiv, ok := indiv.(*HIndividual)

	if !ok {

		return 0, fmt.Errorf("invalid individual type")

	}

	return h(fIndiv.x[0], fIndiv.x[1]), nil

}



func main() {

	pop := evoli.NewPopulation(50)

	for i := 0; i < pop.Cap(); i++ {

		x := rand.Float64()*20 - 10

		y := rand.Float64()*20 - 10

		vx := rand.Float64()*20 - 10

		vy := rand.Float64()*20 - 10

		pop.Add(&HIndividual{

			x: []float64{x, y},

			v: []float64{vx, vy},

		})

	}

	crosser := &HCrosser{}

	mutater := &HMutater{}

	evaluator := &HEvaluater{}

	mutationProbability := .20

	selecter := evoli.NewTruncationSelecter()

	survivorSize := 30



	ga := evoli.NewGenetic(pop, selecter, survivorSize, crosser, mutater, mutationProbability, evaluator)



	for i := 0; i < 100; i++ {

		err := ga.Next()

		if err != nil {

			panic(err)

		}

	}



	// evaluate the latest population

	for _, v := range ga.Population().Slice() {

		f, err := evaluator.Evaluate(v)

		if err != nil {

			panic(err)

		}

		v.SetFitness(f)

	}



	fmt.Printf("Max Value: %.2f\n", ga.Alpha().Fitness())

}

```



```bash

Max Value: 1.00

```



## Issues



If you have any problems or questions, please ask for help through a [GitHub issue](https://github.com/khezen/evoli/issues).



## Contributions



Help is always welcome! For example, documentation (like the text you are reading now) can always use improvement. There's always code that can be improved. If you ever see something you think should be fixed, you should own it. If you have no idea what to start on, you can browse the issues labeled with [help wanted](https://github.com/khezen/evoli/labels/help%20wanted).



As a potential contributor, your changes and ideas are welcome at any hour of the day or night, weekdays, weekends, and holidays. Please do not ever hesitate to ask a question or send a pull request.



[Code of conduct](https://github.com/khezen/evoli/blob/master/CODE_OF_CONDUCT.md).