How to get the gene values for each solution with pygad?

Question

I'm having a problem with pygad. My goal is to minimize the volume of a structure using the Ansys program. The Ansys code should read an input file, where I'm trying to write the values of the genes (project variables) for each evaluation of the fitness function, however, the code doesn't finish.

import pygad
import numpy as np
import subprocess
import time
volu = []
d = []
dmax = 25
gene_space = [range(1,100), range(1,100)]
print(gene_space)



def fitness_function(solution, k):
    """é aqui que está o problema. preciso arrumar uma forma de utilizar os genes gerados pelo algorítmo"""
    pop = ga_instance.population
    with open("C:\\Temp\\exemplo\\VariavelViga.txt", 'w') as f:
        print('B =', '%0.0f' %pop[k, 0], file=f)
        print('H =', '%0.0f' %pop[k, 1], file=f)
    cmd = ["C:\Program Files\ANSYS Inc\\v150\ANSYS\\bin\winx64\ANSYS150.exe", '-b' , '-i' , 'C:\Temp\\exemplo\ExemploViga.txt' , '-o' , 'C:\Temp\exemplo\ExemploViga.out'] 
    subprocess.call(cmd, shell=True)

    objetivo = np.loadtxt("C:\\Temp\\exemplo\\ObjetivoViga.txt")
    volu.append(objetivo[0])
    d.append(objetivo[1])
         
    if pop[k, 0] - pop[k, 1] < 0 and pop[k, 1] - 20*pop[k, 0] < 0 and d[k] - dmax <0:
        fitness = 1/objetivo [0]
    else:
        fitness = -100
    return fitness



ga_instance = pygad.GA(num_generations=15,
                       num_parents_mating=7,
                       fitness_func=fitness_function,
                       sol_per_pop=100,
                       num_genes=2,
                       init_range_low=1,
                       init_range_high=100,
                       parent_selection_type="sss",
                       keep_parents=5,
                       crossover_type="single_point",
                       mutation_type="random",
                       gene_space=gene_space,
                       gene_type=int,
                       mutation_percent_genes= 10)

sol, sol_fitness, sol_idx = ga_instance.best_solution()
print("Parameters of the best solution : {solution}".format(solution=sol))
ga_instance.plot_fitness()

However, after a while, I get the following error:

The plot_fitness() (i.e. plot_result()) method can only be called after completing at least 1 generation but (0) is completed.

I believe the problem is when I try to access the gene values for printing in my input file to Ansys (VariavelViga.txt).

Answer 1

After creating an instance of the pygad.GA class, you should call the run() method to start the evolution.

ga_instance = pygad.GA(...)

ga_instance.run()

...

ga_instance.plot_fitness()

The plot_fitness() method can only be executed after the run() method is executed.

Thanks for using PyGAD!