shakespeare-monkey-problem/Population.js at master · bhanukaManesha/shakespeare-monkey-problem · GitHub

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class Population {
    constructor(mutation_rate, pop_size, target_word) {
        this.population_array = [];
        this.newChar = () => {
            let max = 122;
            let min = 63;
            let c = Math.floor(Math.random() * (+max - +min)) + +min;
            if (c === 63) {
                c = 32;
            }
            if (c === 64) {
                c = 46;
            }
            return String.fromCharCode(c);
        };
        this.target_word = target_word;
        this.mating_pool = [];
        this.pop_size = pop_size;
        this.mutation_rate = mutation_rate;
        //Create population array
        for (let i = 0; i < pop_size; i++) {
            let initial_word = [];
            for (let i = 0; i < target_word.length; i++) {
                initial_word.push(this.newChar());
            }
            this.population_array.push(new Word(this.target_word, initial_word.join("")));
        }
        // console.log(this.population_array)
    }
    naturalSelection() {
        let newPopulation = [];
        for (let i = 0; i < this.population_array.length; i++) {
            let max = this.mating_pool.length;
            let min = 0;
            let index1 = Math.floor(Math.random() * (+max - +min)) + +min;
            let index2 = Math.floor(Math.random() * (+max - +min)) + +min;
            // console.log(this.mating_pool)
            let word1 = this.mating_pool[index1];
            let word2 = this.mating_pool[index2];
            // // Crossover with random length
            let maxLength = word1.getLength();
            let minLength = 0;
            let randomWordIndex = Math.floor(Math.random() * (+maxLength - +minLength)) + +minLength;
            let newWordArray = word1.getWord().slice(0, randomWordIndex).concat(word2.getWord().slice(randomWordIndex, maxLength));
            //Mutation
            for (let i = 0; i < newWordArray.length; i++) {
                let rand = Math.random();
                if (rand < this.mutation_rate) {
                    newWordArray[i] = this.newChar();
                }
            }
            let newWord = newWordArray.join('');
            newPopulation.push(new Word(this.target_word, newWord));
        }
        this.population_array = newPopulation;
    }
    calculateFitness() {
        // Calculate the fitness
        // let max_fitness = 0;
        for (let i = 0; i < this.population_array.length; i++) {
            this.population_array[i].calculateWordFitness();
            // if (this.population_array[i].getFitness() > max_fitness){
            // max_fitness = this.population_array[i].getFitness()
            // }
        }
        let max_word = new Word(this.target_word, this.target_word);
        max_word.calculateWordFitness();
        let max_fitness = max_word.getFitness();
        // Normalized the fitness
        for (let i = 0; i < this.population_array.length; i++) {
            this.population_array[i].setNormalizedFitness((this.population_array[i].getFitness()) / max_fitness);
        }
        this.generateMatingPool();
    }
    generateMatingPool() {
        this.mating_pool = [];
        for (let i = 0; i < this.population_array.length; i++) {
            for (let j = 0; j < Math.floor(this.population_array[i].getNormalizedFitness() * 100); j++) {
                this.mating_pool.push(this.population_array[i]);
            }
        }
    }
    averagefitness() {
        let total_fitness = 0;
        for (let i = 0; i < this.population_array.length; i++) {
            // console.log(this.population_array[i])
            total_fitness += this.population_array[i].getNormalizedFitness();
        }
        return total_fitness / this.pop_size;
    }
    maxfitness() {
        let max_fitness = this.population_array[0].getNormalizedFitness();
        for (let i = 0; i < this.population_array.length; i++) {
            // console.log(this.population_array[i])
            if (this.population_array[i].getNormalizedFitness() > max_fitness) {
                max_fitness = this.population_array[i].getNormalizedFitness();
            }
        }
        return max_fitness;
    }
    minfitness() {
        let min_fitness = this.population_array[0].getNormalizedFitness();
        for (let i = 0; i < this.population_array.length; i++) {
            // console.log(this.population_array[i])
            if (this.population_array[i].getNormalizedFitness() < min_fitness) {
                min_fitness = this.population_array[i].getNormalizedFitness();
            }
        }
        return min_fitness;
    }
    getBestWord() {
        let best_word = this.population_array[0];
        for (let i = 0; i < this.population_array.length; i++) {
            if (this.population_array[i].getFitness() > best_word.getFitness()) {
                best_word = this.population_array[i];
            }
        }
        return best_word.getWord().join('');
    }
    evaluate(best_word) {
        return this.target_word === best_word ? false : true;
    }
}