40 lines
1.2 KiB
Go
40 lines
1.2 KiB
Go
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package gago
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import (
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"errors"
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"math/rand"
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)
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// Migrator applies crossover to the GA level, as such it doesn't
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// require an independent random number generator and can use the global one.
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type Migrator interface {
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Apply(pops Populations, rng *rand.Rand)
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Validate() error
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}
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// MigRing migration exchanges individuals between consecutive Populations in a
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// random fashion. One by one, each population exchanges NMigrants individuals
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// at random with the next population. NMigrants should be higher than the
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// number of individuals in each population, else all the individuals will
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// migrate and it will be as if nothing happened.
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type MigRing struct {
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NMigrants int // Number of migrants per exchange between Populations
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}
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// Apply MigRing.
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func (mig MigRing) Apply(pops Populations, rng *rand.Rand) {
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for i := 0; i < len(pops)-1; i++ {
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for _, k := range randomInts(mig.NMigrants, 0, len(pops[i].Individuals), rng) {
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pops[i].Individuals[k], pops[i+1].Individuals[k] = pops[i+1].Individuals[k], pops[i].Individuals[k]
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}
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}
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}
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// Validate MigRing fields.
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func (mig MigRing) Validate() error {
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if mig.NMigrants < 1 {
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return errors.New("NMigrants should be higher than 0")
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}
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return nil
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}
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