93 lines
4.0 KiB
Python
93 lines
4.0 KiB
Python
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import torch
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import pygad
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from pygad.torchga import torchga
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def fitness_func(solution, sol_idx):
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global data_inputs, data_outputs, torch_ga, model, loss_function
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model_weights_dict = torchga.model_weights_as_dict(model=model,
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weights_vector=solution)
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# Use the current solution as the model parameters.
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model.load_state_dict(model_weights_dict)
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predictions = model(data_inputs)
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abs_error = loss_function(predictions, data_outputs).detach().numpy() + 0.00000001
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solution_fitness = 1.0 / abs_error
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return solution_fitness
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def callback_generation(ga_instance):
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print("Generation = {generation}".format(generation=ga_instance.generations_completed))
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print("Fitness = {fitness}".format(fitness=ga_instance.best_solution()[1]))
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# Create the PyTorch model.
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input_layer = torch.nn.Linear(3, 2)
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relu_layer = torch.nn.ReLU()
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output_layer = torch.nn.Linear(2, 1)
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model = torch.nn.Sequential(input_layer,
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relu_layer,
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output_layer)
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# print(model)
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# Create an instance of the pygad.torchga.TorchGA class to build the initial population.
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torch_ga = torchga.TorchGA(model=model,
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num_solutions=10)
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loss_function = torch.nn.L1Loss()
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# Data inputs
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data_inputs = torch.tensor([[0.02, 0.1, 0.15],
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[0.7, 0.6, 0.8],
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[1.5, 1.2, 1.7],
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[3.2, 2.9, 3.1]])
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# Data outputs
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data_outputs = torch.tensor([[0.1],
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[0.6],
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[1.3],
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[2.5]])
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# Prepare the PyGAD parameters. Check the documentation for more information: https://pygad.readthedocs.io/en/latest/README_pygad_ReadTheDocs.html#pygad-ga-class
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num_generations = 250 # Number of generations.
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num_parents_mating = 5 # Number of solutions to be selected as parents in the mating pool.
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initial_population = torch_ga.population_weights # Initial population of network weights
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parent_selection_type = "sss" # Type of parent selection.
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crossover_type = "single_point" # Type of the crossover operator.
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mutation_type = "random" # Type of the mutation operator.
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mutation_percent_genes = 10 # Percentage of genes to mutate. This parameter has no action if the parameter mutation_num_genes exists.
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keep_parents = -1 # Number of parents to keep in the next population. -1 means keep all parents and 0 means keep nothing.
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ga_instance = pygad.GA(num_generations=num_generations,
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num_parents_mating=num_parents_mating,
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initial_population=initial_population,
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fitness_func=fitness_func,
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parent_selection_type=parent_selection_type,
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crossover_type=crossover_type,
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mutation_type=mutation_type,
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mutation_percent_genes=mutation_percent_genes,
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keep_parents=keep_parents,
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on_generation=callback_generation)
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ga_instance.run()
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# After the generations complete, some plots are showed that summarize how the outputs/fitness values evolve over generations.
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ga_instance.plot_result(title="PyGAD & PyTorch - Iteration vs. Fitness", linewidth=4)
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# Returning the details of the best solution.
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solution, solution_fitness, solution_idx = ga_instance.best_solution()
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print("Fitness value of the best solution = {solution_fitness}".format(solution_fitness=solution_fitness))
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print("Index of the best solution : {solution_idx}".format(solution_idx=solution_idx))
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# Fetch the parameters of the best solution.
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best_solution_weights = torchga.model_weights_as_dict(model=model,
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weights_vector=solution)
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model.load_state_dict(best_solution_weights)
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predictions = model(data_inputs)
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print("Predictions : \n", predictions.detach().numpy())
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abs_error = loss_function(predictions, data_outputs)
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print("Absolute Error : ", abs_error.detach().numpy())
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