I'm trying to figure out how this code works it's suppose to use a genetic algorithm to solve the multiple knapsack problem in python. Could someone eplain how this program reads the data file in and give me another workable instance of a data file. The code is in three files including one data file knapsakc_prob.py code: from genetic_toolkit import Population,Chromosome,BiologicalProcessManager import statistics import random ''' Generation Evaluation Function ''' def find_the_best(population): best = None for individual in population: if best == None or individual.fitness > best.fitness: best = individual return best.fitness # Global Variables crossover_rate = 0.70 # Initialize population with random candidate solutions population = Population(500) population.initialize_population() # Set the mutation rate mutation_rate = 1/population.populationSize # Get a reference to the number of knapsacks numberOfKnapsacks = population.numberOfKnapsacks generation_counter = 0 while(generation_counter != 100): current_population_fitnesses = [chromosome.fitness for chromosome in population.population] print("CURRENT GEN FITNESS: {} ".format(current_population_fitnesses)) new_gen = [] while(len(new_gen) != population.populationSize): # Create tournament for tournament selection process tournament = [population.population[random.randint(1, population.populationSize-1)] for individual in range(1, population.populationSize)] # Obtain two parents from the process of tournament selection parent_one, parent_two = population.select_parents(tournament) # Create the offspring from those two parents child_one,child_two = BiologicalProcessManager.crossover(crossover_rate,parent_one,parent_two) # Try to mutate the children BiologicalProcessManager.mutate(mutation_rate, child_one, numberOfKnapsacks) BiologicalProcessManager.mutate(mutation_rate, child_two, numberOfKnapsacks) # Evaluate each of the children child_one.generateFitness(population.knapsackList) child_two.generateFitness(population.knapsackList) # Add the children to the new generation of chromsomes new_gen.append(child_one) new_gen.append(child_two) # Replace old generation with the new one population.population = new_gen generation_counter += 1 genetic-toolkit.py code: import random import linecache import copy from collections import namedtuple # Class to represent biological processes class BiologicalProcessManager: ''' Crossover Function - The process of One-Point crossover is exercised in this function. ''' def crossover(crossover_rate, parentOne, parentTwo): random_probability = random.random() if random_probability < crossover_rate: return (parentOne, parentTwo) else: pivot = random.randint(0, len(parentOne.genotype_representation)-1) child_one_genotype = parentOne.genotype_representation[:pivot] + parentTwo.genotype_representation[pivot:] child_two_genotype = parentTwo.genotype_representation[:pivot] + parentOne.genotype_representation[pivot:] child_one = Chromosome(parentOne.numberOfKnapsacksReference, parentOne.numberOfObjectsReference, child_one_genotype) child_two = Chromosome(parentOne.numberOfKnapsacksReference, parentOne.numberOfObjectsReference, child_two_genotype) child_one.phenotype_representation = parentOne.phenotype_representation child_two.phenotype_representation = parentOne.phenotype_representation return (child_one, child_two) ''' Mutation function - The process of Random Resetting is exercised in this function. ''' def mutate(mutation_rate, child, numberOfKnapsacks): for index, position in enumerate(child.genotype_representation): random_probability = random.random() ''' (Random Resetting) "Flip" the position with another knapsack if probability < mutation_rate ''' if random_probability < mutation_rate: child.genotype_representation[index] = random.randint(0,numberOfKnapsacks) # Class to represent chromosome class Chromosome: fitness = None # Chromosomes fitness phenotype_representation = None # Phenotype representation def __init__(self, numOfKnapsacks, numOfObjects, genotype_representation = None): self.numberOfKnapsacksReference = numOfKnapsacks self.numberOfObjectsReference = numOfObjects if genotype_representation == None: self.genotype_representation = [random.randint(0,(numOfKnapsacks)) for x in range(0, numOfObjects)] else: self.genotype_representation = genotype_representation self.length_of_encoding = len(self.genotype_representation) ''' Generates a fitness for all the chromosomes by aggregating their benefits/values ''' def generateFitness(self, knapsackList): ''' Make a copy of the knapsack list to be used to evaluate if objects in the chromsome exceed C using the 'amountUsed' attribute ''' #print("ORIGINAL CHROM: {}".format(self.genotype_representation)) knapsacks = copy.deepcopy(knapsackList) fitnessScore = 0 done = False for i, placement_of_object in enumerate(self.genotype_representation): if placement_of_object == 0: continue else: for knapsack in knapsacks: if knapsack.id == placement_of_object: # if it's over the capacity, change it's bag and revaluate if self.phenotype_representation[i].weight > knapsack.capacity: while(not done): self.genotype_representation[i] = random.randint(0,(self.numberOfKnapsacksReference)) if self.genotype_representation[i] == 0: break else: current_knapsack = next((sack for sack in knapsacks if sack.id == self.genotype_representation[i]),None) if self.phenotype_representation[i].weight > current_knapsack.capacity: continue if self.phenotype_representation[i].weight <= current_knapsack.capacity: fitnessScore += self.phenotype_representation[i].value '''We now subtract the objects weight by the knapsacks capacity so that we can keep track of how much space the knapsack has left in the event that another object goes into the same knapsack ''' current_knapsack.capacity = (current_knapsack.capacity - self.phenotype_representation[i].weight) break else: fitnessScore += self.phenotype_representation[i].value '''We now subtract the objects weight by the knapsacks capacity so that we can keep track of how much space the knapsack has left in the event that another object goes into the same knapsack ''' knapsack.capacity = (knapsack.capacity - self.phenotype_representation[i].weight) # update the chromosomes fitness self.fitness = fitnessScore class Knapsack: def __init__(self, id, capacity): self.id = id self.capacity = capacity class Population: Phenotype = namedtuple('Phenotype', 'id weight value') knapsackList = [] # list of knapsacks knapSackEvaluationList = [] # used for generating fitness of chromosomes population = [] def __init__(self, size): self.populationSize = size self.numberOfKnapsacks = 0 def select_parents(self,tournament): ''' Tournament selection is being used to find two parents ''' first_fittest_indiv = None second_fittest_indiv = None for individual in tournament: # Check if this indivudal is fitter than the current fittist individual if first_fittest_indiv == None or individual.fitness > first_fittest_indiv.fitness: first_fittest_indiv = individual tournament.remove(first_fittest_indiv) for individual in tournament: # Check if this indivudal is fitter than the current fittist individual if second_fittest_indiv == None or individual.fitness > second_fittest_indiv.fitness: second_fittest_indiv = individual #print("FIRST: {}, SECOND: {}".format(first_fittest_indiv.fitness,second_fittest_indiv.fitness)) return (first_fittest_indiv,second_fittest_indiv) def initialize_population(self): ''' Read from a file and create the chromosomes ''' # Open data file dataFile = open('data.txt','r') # Read how many knapsacks there will be. (We read the first byte) numOfKnapsacks = int(dataFile.read(1)) self.numberOfKnapsacks = numOfKnapsacks #print("NUMBER OF KNAPSACKS: {} ".format(numOfKnapsacks)) dataFile.seek(0,0); # Read how many objects there will be. numOfObjects = int(dataFile.readlines()[numOfKnapsacks+1]) # Create knapsack dictionary lines_to_read = [] for num in range(0, numOfKnapsacks): lines_to_read.append(num) dataFile.seek(0,0) for i,line in enumerate(dataFile): if i == 0: continue elif i > 0 and i < numOfKnapsacks + 1: capacity = int(line) self.knapsackList.append(Knapsack((i), capacity)) # Create phenotype representation of chromosome phenotype_representation = [] lineNumberOffset = numOfKnapsacks + 3 # file offset used to find the objects in the file for i in range(0,numOfObjects): value,weight = linecache.getline("data.txt", lineNumberOffset+i).split() # Create the phenotype representation for each chromsome phenotype_representation.append(self.Phenotype(i, int(value),int(weight))) # Create the initial population for j in range(0,self.populationSize): # Create a new chromosome new_chromosome = Chromosome(numOfKnapsacks,numOfObjects) # Give each chromosome it's phenotype representation new_chromosome.phenotype_representation = phenotype_representation # Evaluate each chromosome new_chromosome.generateFitness(self.knapsackList) # Add the chromsome to the population self.population.append(new_chromosome) dataFile.close() data.txt: 4 60 92 120 200 12 20 92 34 57 22 49 48 68 51 60 39 43 61 67 82 84 84 87 87 72 20 87 10 72