heuristic.py

from math import sqrt
from numpy import array, where


class Heuristic:
    def __init__(self, current_node, final_node, heuristic):
        self.current_node = current_node
        self.final_node = final_node
        self.size = len(current_node.puzzle)
        self.heuristic = heuristic

    def misplaced(self):
        current = [y for x in self.current_node.puzzle for y in x]
        final = [y for x in self.final_node.puzzle for y in x]
        h_score = 0
        i = 0
        while i < len(current):
            if current[i] != final[i] and current[i] != 0:
                h_score += 1
            i += 1

        return h_score

    @staticmethod
    def get_coordinates(puzzle, item):
        arr = array(puzzle)
        return int(where(arr == item)[0]), int(where(arr == item)[1])

    def manhatten(self):
        h_score = 0

        for x in range(self.size):
            for y in range(self.size):
                if self.current_node.puzzle[x][y] != 0:
                    x_goal, y_goal = self.get_coordinates(puzzle=self.final_node.puzzle, item=self.current_node.puzzle[x][y])
                    dx, dy = abs(x_goal - x), abs(y_goal - y)
                    h_score += dx + dy

        return h_score

    def euclidean(self):
        h = 0
        for x in range(self.size):
            for y in range(self.size):
                if self.current_node.puzzle[x][y] != 0:
                    x_goal, y_goal = self.get_coordinates(puzzle=self.final_node.puzzle, item=self.current_node.puzzle[x][y])
                    dx, dy = abs(x_goal - x), abs(y_goal - y)
                    h += sqrt(dx * dx + dy * dy)
        return h

    def calculate(self):
        if self.heuristic == 'misplaced':
            return self.misplaced()
        elif self.heuristic == 'manhatten':
            return self.manhatten()
        elif self.heuristic == 'euclidian':
            return self.euclidean()

# if __name__ == "__main__":
#     h_score = 0
#     final_node = [[1, 2, 3],
#                   [8, 0, 4],
#                   [7, 6, 5]]
#     current_node = [[1, 2, 3],
#                     [8, 4, 5],
#                     [0, 7, 6]]
#     for x in range(3):
#         for y in range(3):
#             if current_node[x][y] != 0:
#                 x_goal, y_goal = Heuristic.get_coordinates(puzzle=final_node,
#                                                            item=current_node[x][y])
#                 dx, dy = abs(x_goal - x), abs(y_goal - y)
#                 print(current_node[x][y], dx + dy)
#                 h_score += dx + dy
#
#     print(h_score)