如何解决算法可视化工具DFS实现错误
该算法直接向上搜索，当它到达障碍时，它只是停止而不是向右移动 Here。 我是图算法的新手，并且刚刚了解它们，所以在实现它们时我一无所知。
我的代码尚未优化，但是，稍后我将对其进行优化。这是我的代码：
import pygame
import queue
WIDTH = 720
pygame.init()
WIN = pygame.display.set_mode((WIDTH,WIDTH))
pygame.display.set_caption("Pathfinding Visualizer")
RED = (255,0)
GREEN = (0,255,0)
BLUE = (0,0)
YELLOW = (255,0)
WHITE = (255,255)
BLACK = (0,0)
PURPLE = (128,128)
ORANGE = (255,165,0)
GREY = (128,128,128)
TURQUOISE = (64,224,208)
class Node:
def __init__(self,row,col,width,total_rows):
self.row = row
self.col = col
self.width = width
self.x = row * width
self.y = col * width
self.color = WHITE
self.neighbours = []
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 == PURPLE
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_neighbours(self,grid):
self.neighbours = []
if self.row < self.total_rows - 1 and not grid[self.row + 1][self.col].is_barrier(): # DOWN
self.neighbours.append(grid[self.row + 1][self.col])
if self.row > 0 and not grid[self.row - 1][self.col].is_barrier(): # UP
self.neighbours.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.neighbours.append(grid[self.row][self.col + 1])
if self.col > 0 and not grid[self.row][self.col - 1].is_barrier(): # LEFT
self.neighbours.append(grid[self.row][self.col - 1])
def __lt__(self,other):
return False
def h(p1,p2):
x1,y1 = p1
x2,y2 = p2
return abs(x1 - x2) + abs(y1 - y2)
def reconstruct_path(came_from,current,draw):
print(came_from)
while current in came_from:
current = came_from[current]
current.make_path()
draw()
def dfs(draw,grid,start,end):
open_set = queue.LifoQueue()
open_set.put(start)
came_from = {}
g = {node: float("inf") for row in grid for node in row}
g[start] = 0
open_set_hash = {start}
while not open_set.empty():
for event in pygame.event.get():
if event.type == pygame.QUIT:
pygame.quit()
if event.type == pygame.KEYDOWN:
if event.key == pygame.K_c:
return False
current = open_set.get()
open_set_hash.remove(current)
if current == end:
reconstruct_path(came_from,end,draw)
end.make_end()
start.make_start()
return True,g
for n in current.neighbours:
g[n] = g[current] + 1
came_from[n] = current
if n not in open_set_hash:
open_set.put(n)
open_set_hash.add(n)
draw()
if current != start:
current.make_closed()
return False
def astar(draw,end):
count = 0
open_set = queue.PriorityQueue()
open_set.put(item=(0,count,start))
came_from = {}
g = {node: float("inf") for row in grid for node in row}
g[start] = 0
f = {node: float("inf") for row in grid for node in row}
f[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()
if event.type == pygame.KEYDOWN:
if event.key == pygame.K_c:
return False
current = open_set.get()[2]
open_set_hash.remove(current)
if current == end:
reconstruct_path(came_from,g
for neighbour in current.neighbours:
temp_g = g[current] + 1
if temp_g < g[neighbour]:
came_from[neighbour] = current
g[neighbour] = temp_g
f[neighbour] = temp_g + h(neighbour.get_pos(),end.get_pos())
if neighbour not in open_set_hash:
count += 1
open_set.put((f[neighbour],neighbour))
open_set_hash.add(neighbour)
neighbour.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):
# If rows = 5,then grid would be [[],[],[]]
grid.append([])
for j in range(rows):
node = Node(i,j,gap,rows)
if i == 0 or j == 0 or i == 59 or j == 59:
node.make_barrier()
grid[i].append(node)
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,(j*gap,0),width))
def draw_text(win):
font = pygame.font.Font(None,20)
text1 = font.render("DepthFirstSearch - D",1,(255,255))
text2 = font.render("BreadthFirstSearch - B",255))
text3 = font.render("AStar - A",255))
textpos1 = text1.get_rect()
textpos2 = text2.get_rect()
textpos3 = text3.get_rect()
textpos1.centerx = win.get_rect().centerx-290
textpos2.centerx = win.get_rect().centerx-125
textpos3.centerx = win.get_rect().centerx+10
win.blit(text1,textpos1)
win.blit(text2,textpos2)
win.blit(text3,textpos3)
def draw(win,width):
win.fill(WHITE)
for row in grid:
for node in row:
node.draw(win)
draw_grid(win,width)
draw_text(win)
pygame.display.update()
def get_clicked_pos(pos,width):
gap = width // rows
y,x = pos
row = y // gap
col = x // gap
return row,col
def main(win,width):
ROWS = 60
grid = make_grid(ROWS,width)
start = None
end = None
run = True
started = False
while run:
draw(win,ROWS,width)
for event in pygame.event.get():
if event.type == pygame.QUIT:
run = False
if started:
continue
if pygame.mouse.get_pressed()[0]: # LEFT
pos = pygame.mouse.get_pos()
row,col = get_clicked_pos(pos,width)
node = grid[row][col]
if not start and node != end and node.is_barrier() == False:
start = node
start.make_start()
elif not end and node != start and node.is_barrier() == False:
end = node
end.make_end()
elif node != end and node != start:
node.make_barrier()
elif pygame.mouse.get_pressed()[2]: # RIGHT
pos = pygame.mouse.get_pos()
row,width)
node = grid[row][col]
node.reset()
if node == start:
start = None
elif node == end:
end = None
if event.type == pygame.KEYDOWN:
if event.key == pygame.K_a and start and end:
for row in grid:
for node in row:
node.update_neighbours(grid)
astar(lambda: draw(win,width),end)
elif event.key == pygame.K_d and start and end:
for row in grid:
for node in row:
node.update_neighbours(grid)
dfs(lambda: draw(win,end)
elif event.key == pygame.K_b and start and end:
for row in grid:
for node in row:
node.update_neighbours(grid)
# bfs(lambda: draw(win,end)
if event.key == pygame.K_c:
start = None
end = None
grid = make_grid(ROWS,width)
pygame.quit()
main(WIN,WIDTH)
解决方法
我评论了您的open_set_hash.remove(current)。我不明白为什么要从访问列表中删除当前内容？也将came_from[n] = current移至if条件内。这是为了使reconstruct_path函数正常工作。
if n not in open_set_hash:
came_from[n] = current
此后看来效果很好。顺便说一句。您进行了很好的可视化！
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