python - 计算 A* 寻路算法的执行时间时，Python 列表中缺少项目

Question

我构建了一个 A* 寻路算法，可以找到从 A 点到 B 点的最佳路线，有一个计时器在算法执行后启动和结束，并绘制路径，将其解析为全局变量。因此，当我多次运行算法(以获得平均时间)时，它是可以访问的。

全局变量被添加到列表中，除了当我运行算法 5 次时，仅添加 4 个值(我可以看到记录了 5 次，因为算法在完成后打印了时间)。当显示列表时，它总是第一次错过，并且如果我运行算法 5 次，则只有 2,3,4,5 次。这是main.py

import astar


import pygame

def main():
    timing_list = []
    WIDTH = 800
    WIN = pygame.display.set_mode((WIDTH, WIDTH))
    for x in range(0, 4):
        astar.main(WIN, WIDTH)
        timing_list.insert(x, astar.full_time)
    print(timing_list)


if __name__ == "__main__":
    main()

和

astar.py
from queue import PriorityQueue
from random import randint

import pygame

from timing import Timing

WIDTH = 800
WIN = pygame.display.set_mode((WIDTH, WIDTH))
pygame.display.set_caption("A* Path Finding Algorithm")

RED = (255, 0, 0)
GREEN = (0, 255, 0)
BLUE = (0, 255, 0)
YELLOW = (255, 255, 0)
WHITE = (255, 255, 255)
BLACK = (0, 0, 0)
PURPLE = (128, 0, 128)
ORANGE = (255, 165, 0)
GREY = (128, 128, 128)
TURQUOISE = (64, 224, 208)

global full_time

class Spot:
    def __init__(self, row, col, width, total_rows):
        self.row = row
        self.col = col
        self.x = row * width
        self.y = col * width
        self.color = WHITE
        self.neighbors = []
        self.width = width
        self.total_rows = total_rows

    def get_pos(self):
        return self.row, self.col

    def is_closed(self):
        return self.color == RED

    def is_open(self):
        return self.color == GREEN

    def is_barrier(self):
        return self.color == BLACK

    def is_start(self):
        return self.color == ORANGE

    def is_end(self):
        return self.color == TURQUOISE

    def reset(self):
        self.color = WHITE

    def make_start(self):
        self.color = ORANGE

    def make_closed(self):
        self.color = RED

    def make_open(self):
        self.color = GREEN

    def make_barrier(self):
        self.color = BLACK

    def make_end(self):
        self.color = TURQUOISE

    def make_path(self):
        self.color = PURPLE

    def draw(self, win):
        pygame.draw.rect(win, self.color, (self.x, self.y, self.width, self.width))

    def update_neighbors(self, grid):
        self.neighbors = []
        if self.row < self.total_rows - 1 and not grid[self.row + 1][self.col].is_barrier():  # DOWN
            self.neighbors.append(grid[self.row + 1][self.col])

        if self.row > 0 and not grid[self.row - 1][self.col].is_barrier():  # UP
            self.neighbors.append(grid[self.row - 1][self.col])

        if self.col < self.total_rows - 1 and not grid[self.row][self.col + 1].is_barrier():  # RIGHT
            self.neighbors.append(grid[self.row][self.col + 1])

        if self.col > 0 and not grid[self.row][self.col - 1].is_barrier():  # LEFT
            self.neighbors.append(grid[self.row][self.col - 1])

    def __lt__(self, other):
        return False


def generate_num(x, y):
    return randint(x, y)


def h(p1, p2):
    x1, y1 = p1
    x2, y2 = p2
    return abs(x1 - x2) + abs(y1 - y2)


def reconstruct_path(came_from, current, draw):
    while current in came_from:
        current = came_from[current]
        current.make_path()
        draw()


def algorithm(draw, grid, start, end):
    count = 0
    open_set = PriorityQueue()
    open_set.put((0, count, start))
    came_from = {}
    g_score = {spot: float("inf") for row in grid for spot in row}
    g_score[start] = 0
    f_score = {spot: float("inf") for row in grid for spot in row}
    f_score[start] = h(start.get_pos(), end.get_pos())

    open_set_hash = {start}

    while not open_set.empty():
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                pygame.quit()

        current = open_set.get()[2]
        open_set_hash.remove(current)

        if current == end:
            reconstruct_path(came_from, end, draw)
            end.make_end()
            return True

        for neighbor in current.neighbors:
            temp_g_score = g_score[current] + 1

            if temp_g_score < g_score[neighbor]:
                came_from[neighbor] = current
                g_score[neighbor] = temp_g_score
                f_score[neighbor] = temp_g_score + h(neighbor.get_pos(), end.get_pos())
                if neighbor not in open_set_hash:
                    count += 1
                    open_set.put((f_score[neighbor], count, neighbor))
                    open_set_hash.add(neighbor)
                    neighbor.make_open()

        draw()

        if current != start:
            current.make_closed()

    return False


def make_grid(rows, width):
    grid = []
    gap = width // rows
    for i in range(rows):
        grid.append([])
        for j in range(rows):
            spot = Spot(i, j, gap, rows)
            grid[i].append(spot)

    return grid


def draw_grid(win, rows, width):
    gap = width // rows
    for i in range(rows):
        pygame.draw.line(win, GREY, (0, i * gap), (width, i * gap))
        for j in range(rows):
            pygame.draw.line(win, GREY, (j * gap, 0), (j * gap, width))


def draw(win, grid, rows, width):
    win.fill(WHITE)

    for row in grid:
        for spot in row:
            spot.draw(win)

    draw_grid(win, rows, width)
    pygame.display.update()


def get_clicked_pos(pos, rows, width):
    gap = width // rows
    y, x = pos

    row = y // gap
    col = x // gap

    return row, col


def main(win, width):
    rows = 50
    grid = make_grid(rows, width)

    start = None
    end = None

    t = Timing()
    run = True
    setup_config = True

    while run:
        draw(win, grid, rows, width)
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                run = False
                setup_config = False
            if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_ESCAPE:
                    run = False
                    setup_config = False

            while setup_config:

                for x in range(0, 800):
                    row_pos = generate_num(0, rows - 1)
                    col_pos = generate_num(0, rows - 1)
                    spot = grid[row_pos][col_pos]
                    if not start and spot != end:
                        start = spot
                        start.make_start()

                    elif not end and spot != start:
                        end = spot
                        end.make_end()

                    elif spot != end and spot != start:
                        spot.make_barrier()

                t.start()
                for row in grid:
                    for spot in row:
                        spot.update_neighbors(grid)

                algorithm(lambda: draw(win, grid, rows, width), grid, start, end)
                global full_time
                full_time = t.stop()

                setup_config = False
                run = False

    pygame.QUIT

main(WIN, WIDTH)

和timing.py我的计时器类

import time


class TimerError(Exception):
    """A custom exception used to report errors in use of Timer class"""


class Timing:

    def __init__(self):

        self._start_time = None

    def start(self):

        """Start a new timer"""

        if self._start_time is not None:
            raise TimerError(f"Timer is running. Use .stop() to stop it")

        self._start_time = time.perf_counter()

    def stop(self):

        """Stop the timer, and report the elapsed time"""

        if self._start_time is None:
            raise TimerError(f"Timer is not running. Use .start() to start it")

        elapsed_time = time.perf_counter() - self._start_time

        self._start_time = None

        print(f"Elapsed time: {elapsed_time:0.4f} seconds")
        return elapsed_time

    

Answer 1

编辑:

神秘的第五张打印品当然来自这条线

full_time = t.stop()

通过主循环 4 次迭代，您将到达该行 5 次。这就是您有 5 张照片的原因。

当您使用命令导入 astar 时，您的评论非常正确

import astar

在你的 main.py 文件中，你正在执行 astar.py 末尾的 main(WIN, WIDTH) 。从而产生 5 份打印品。

---

>>> for i in range(0, 4):
...     print(i)
... 
0
1
2
3
>>> 

主 for 循环迭代 4 次，每次都将一个元素插入到空列表中。顺便说一句，我希望这样而不是麻烦的插入。

list.append(astar.full_time) # append inserts at the end of the list

我很惊讶你有 5 个格式的输出

print(f"Elapsed time: {elapsed_time:0.4f} seconds")

顺便说一句，我也想知道你为什么有这些说法:

run = True
while run:
    run = False

以及一个类似的语句，其中包含一个名为 setup_config 的 bool 值和一段时间。您可以通过抑制此 while 来获得更清晰的代码，因为它只执行一次。如果我错了或者我遗漏了您的上下文中的某些内容，请纠正我。