a_pathfinding.py

import pygame
import math
from queue import PriorityQueue
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)


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.width=width
        self.color=WHITE
        self.neighbors=[]
        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 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]
        


        if current == end:
            reconstruct_path(came_from,end,draw)
            end.make_end()
            start.make_start()

            return True# make_path

        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))
                    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

    run=True
    started=False

    while run:
        draw(win,grid,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,ROWS,width)
                spot = grid[row][col]
                if not start:
                    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()

            elif pygame.mouse.get_pressed()[2]: #RIGHT
                pos=pygame.mouse.get_pos()
                row,col=get_clicked_pos(pos,ROWS,width)
                spot=grid[row][col]
                spot.reset()
                if spot==start:
                    start=None
                elif spot==end:
                    end=None

            if event.type==pygame.KEYDOWN:
                if event.key== pygame.K_SPACE and start and end:
                    for row in grid:
                        for spot in row:
                            spot.update_neighbors(grid)
                    algorithm(lambda :draw(win,grid,ROWS,WIDTH),grid,start,end)
                if event.key==pygame.K_c:
                    start=None
                    end=None
                    grid=make_grid(ROWS,width)




    pygame.quit()

main(WIN,WIDTH)