115 lines
3.0 KiB
Python
115 lines
3.0 KiB
Python
from __future__ import annotations
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from dataclasses import dataclass, field
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from enum import Enum, unique
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from typing import Tuple, Optional, List
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from common.constants import ROWS, COLUMNS
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FREE_FIELD = ' '
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@unique
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class Direction(Enum):
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LEFT = (0, -1)
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RIGHT = (0, 1)
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UP = (-1, 0)
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DOWN = (1, 0)
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@unique
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class Action(Enum):
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TURN_LEFT = 'TURN_LEFT'
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TURN_RIGHT = 'TURN_RIGHT'
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FORWARD = 'FORWARD'
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@dataclass
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class State:
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position: Tuple[int, int]
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direction: Direction
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@dataclass
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class Node:
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state: State
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parent: Optional[Node]
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action: Action
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cost: int = field(init=False)
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depth: int = field(init=False)
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def __post_init__(self) -> None:
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self.cost = 0 if not self.parent else self.parent.cost + 1
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self.depth = self.cost
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def __eq__(self, other: Node) -> bool:
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return self.state == other.state
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def __hash__(self) -> int:
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return hash(self.state)
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def expand(node: Node) -> List[Node]:
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return [child_node(node=node, action=action) for action in actions(node.state)]
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def child_node(node: Node, action: Action) -> Node:
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next_state = result(state=node.state, action=action)
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return Node(state=next_state, parent=node, action=action)
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def next_position(current_position: Tuple[int, int], direction: Direction) -> Tuple[int, int]:
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x1, y1 = direction.value
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x2, y2 = current_position
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return x1 + x2, y1 + y2
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def valid_move(position: Tuple[int, int], grid: List[List[str]]) -> bool:
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row, col = position
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return grid[row][col] == FREE_FIELD
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def actions(state: State, grid: List[List[str]]) -> List[Action]:
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possible_actions = [Action.FORWARD, Action.TURN_LEFT, Action.TURN_RIGHT]
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row, col = state.position
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direction = state.direction
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if direction == Direction.UP and row == 0:
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remove_forward(possible_actions)
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if direction == Direction.DOWN and row == ROWS - 1:
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remove_forward(possible_actions)
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if direction == Direction.LEFT and col == 0:
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remove_forward(possible_actions)
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if direction == Direction.RIGHT and col == COLUMNS - 1:
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remove_forward(possible_actions)
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if not valid_move(next_position(state.position, direction), grid):
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remove_forward(possible_actions)
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return possible_actions
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def remove_forward(possible_actions: List[Action]) -> None:
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if Action.FORWARD in possible_actions:
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possible_actions.remove(Action.FORWARD)
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def result(state: State, action: Action, grid: List[List[str]]) -> State:
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pass
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def goal_test(state: State, goal_list: List[Tuple[int, int]]) -> bool:
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return state.position in goal_list
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def h(state: State, goal: Tuple[int, int]) -> int:
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"""heuristics that calculates Manhattan distance between current position and goal"""
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x1, y1 = state.position
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x2, y2 = goal
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return abs(x1 - x2) + abs(y1 - y2) # Manhattan distance
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def f(current_node: Node, goal: Tuple[int, int]) -> int:
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"""f(n) = g(n) + h(n), g stands for current cost, h for heuristics"""
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return current_node.cost + h(state=current_node.state, goal=goal)
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