individual.py

import numpy as np

from .problem import KnapsackProblem


class Individual:
    def __init__(self, chromosome_length: int) -> None:
        if chromosome_length <= 0:
            raise ValueError("chromosome_length must be > 0")
        self.genes: np.ndarray = np.zeros(chromosome_length, dtype=bool)
        self.fitness: int = 0
        self.total_value: int = 0
        self.total_weight: int = 0

    @classmethod
    def random(cls, chromosome_length: int, rng: np.random.Generator) -> "Individual":
        instance = cls(chromosome_length)
        instance.genes = rng.integers(0, 2, size=chromosome_length, dtype=bool)
        return instance

    @classmethod
    def copy_of(cls, other: "Individual") -> "Individual":
        instance = cls(other.chromosome_length())
        instance.genes = other.genes.copy()
        instance.fitness = other.fitness
        instance.total_value = other.total_value
        instance.total_weight = other.total_weight
        return instance

    def chromosome_length(self) -> int:
        return int(self.genes.size)

    def gene(self, index: int) -> bool:
        return bool(self.genes[index])

    def set_gene(self, index: int, value: bool) -> None:
        self.genes[index] = value

    def flip_gene(self, index: int) -> None:
        self.genes[index] = not self.genes[index]

    def evaluate(self, problem: KnapsackProblem) -> None:
        values = problem._values_array
        weights = problem._weights_array
        self.total_value = int((self.genes * values).sum())
        self.total_weight = int((self.genes * weights).sum())
        # kara za nadwagę: osobnik niedopuszczalny dostaje fitness 0 i przegrywa każdy turniej
        self.fitness = self.total_value if self.total_weight <= problem.capacity else 0