Source code for jinete.algorithms.heuristics.local_search.algorithm

from __future__ import (
    annotations,
)

import logging
from typing import (
    TYPE_CHECKING,
)

from ....models import (
    Planning,
)
from ...abc import (
    Algorithm,
)
from .strategies import (
    ReallocationLocalSearchStrategy,
)

if TYPE_CHECKING:
    from typing import Set
    from ....models import (
        Result,
        Route,
    )
    from .strategies import LocalSearchStrategy

logger = logging.getLogger(__name__)


class LocalSearchAlgorithm(Algorithm):
    def __init__(
        self,
        initial: Result,
        no_improvement_threshold: int = 1,
        strategy_cls: LocalSearchStrategy = None,
        *args,
        **kwargs
    ):
        super().__init__(*args, **kwargs)
        if strategy_cls is None:
            strategy_cls = ReallocationLocalSearchStrategy

        self.initial = initial
        self.args = args
        self.kwargs = kwargs
        self.strategy_cls = strategy_cls
        self.no_improvement_threshold = no_improvement_threshold

    @property
    def _initial_planning(self) -> Planning:
        return self.initial.planning

    @property
    def _initial_routes(self) -> Set[Route]:
        return self._initial_planning.routes

    def _optimize(self) -> Planning:
        best = self.initial

        no_improvement_count = 0
        while no_improvement_count < self.no_improvement_threshold:
            no_improvement_count += 1

            current = self.strategy_cls(best).improve()
            best = self._objective.best(best, current)

            if best == current:
                no_improvement_count = 0

        assert best is not None

        return best.planning