'mutation_type = None' not allowed

[mathlusiverse]

I did not use mutation, pygad print the following warning:

If you do not want to mutate any gene, please set mutation_type=None.

But when I set mutation_type=None, or mutation_type="None", then pygad crashed:

  File "C:\My\MyPythonProject\GeneticAlgo\venv\lib\site-packages\pygad\pygad.py", line 282, in __init__
    raise TypeError("The expected type of the 'mutation_type' parameter is str but ({mutation_type}) found.".format(mutation_type=type(mutation_type)))
TypeError: The expected type of the 'mutation_type' parameter is str but (<class 'NoneType'>) found.

I looked at the source code, it seems that line 280 does not allow the possibility of mutation_type being None. Yet line 295 does allow such possibility.

[ahmedfgad]

Thank you. The issue with assigning None values for crossover_type and mutation_type is solved. The updated pygad.py module is available at GitHub and a new release will be published to PyPI later. Please try the updated module if there a chance.

[mathlusiverse]

Thanks, @ahmedfgad for the quick response! Please keep up the good work.

I will test it after you make it available on your web page.

[ahmedfgad]

Thank you.

[ahmedfgad]

Hi @ahmedfgad thanks a lot for this wonderful tool. I tried to run the example code from

/home/sikari/Desktop/temp_proj_pygad/PYGAD/pygad.py:374: UserWarning: The percentage of genes to mutate (mutation_percent_genes=10) resutled in selecting (0) genes. The number of genes to mutate is set to 1 (mutation_num_genes=1).
If you do not want to mutate any gene, please set mutation_type=None.
if not self.suppress_warnings: warnings.warn("The percentage of genes to mutate (mutation_percent_genes={mutation_percent}) resutled in selecting ({mutation_num}) genes. The number of genes to mutate is set to 1 (mutation_num_genes=1).\nIf you do not want to mutate any gene, please set mutation_type=None.".format(mutation_percent=mutation_percent_genes, mutation_num=mutation_num_genes))

solution, solution_fitness, solution_idx = ga_instance.best_solution()
print("Parameters of the best solution : {solution}".format(solution=solution))
Parameters of the best solution : [ 4.46054413 -0.56253708 -0.58246418 1.96274254 -2.26517722 1.62457641]
print("Fitness value of the best solution = {solution_fitness}".format(solution_fitness=solution_fitness))
Fitness value of the best solution = 42.05377974846767

`

Hi @asishadhikari ,

This is a normal warning and you can supress all warnings by setting suppress_warnings=True.

The warning is returned because you use the default of mutating 10% of the genes (mutation_percent_genes=10). When you have few genes like only 2, then 10% means 0.2 genes which is rounded to 0. This means you are mutating 0 genes. With that situation, the number of genes is raised to 1 automatically.

This warning tells you that if you intentionally want to mutate no genes, then it is better to set mutation_type=None. Otherwise, there will be 1 gene mutated.

Please let me know if I should clarify something.

[ahmedfgad]

This issue is solved in the new release of PyGAD 2.14.0.
Thank you.