I am trying to show the path taken for this Dijkstra's algo, however, once the program ends, it should display the path taken and how many steps it has taken. But it only shows the end_pos and 1 step I have looked over the code multiple times but maybe im too tired to recognise the mistake or im just stupid.... Anyone have any idea?
# imports go here
class DijkstraPathfinder:
#staticmethod
def find_path():
def _get_start_and_end_pos():
start_pos, end_pos = None, None
for row in grid:
for square in row:
if square.state == SquareState.START:
start_pos = square.row, square.col
elif square.state == SquareState.END:
end_pos = square.row, square.col
return start_pos, end_pos
def _get_valid_neighbours(r: int, c: int):
"""
Find valid neighbours for a square:
valid means it's not a wall, has not been visited
:param r: row
:param c: column
:return: valid neighbours
:rtype: list()
"""
up_neighbour = (r, c + 1)
down_neighbour = (r, c - 1)
left_neighbour = (r - 1, c)
right_neighbour = (r + 1, c)
neighbours = [up_neighbour, down_neighbour, left_neighbour, right_neighbour]
v_neighbours = list()
for neighbour in neighbours:
r, c = neighbour
if r in range(settings.ROWS) and c in range(settings.ROWS):
if grid[r][c].state not in [SquareState.VISITED, SquareState.WALL, SquareState.START]:
v_neighbours.append(neighbour)
return v_neighbours
def _reconstruct_path():
path = [end_pos]
current = end_pos
while prev[current]:
path.append(prev[current])
current = prev[current]
# print(u)
path.reverse()
return path
WINDOW = pygame.display.set_mode((800, 800))
grid = Creator.get_grid()
start_pos, end_pos = _get_start_and_end_pos()
print()
print(f'Starting position: {start_pos}')
print(f'Ending position: {end_pos}')
print()
dist = {}
prev = {}
q = list()
finished = False
while not finished:
for row in grid:
for square in row:
pos = square.get_pos()
dist[square.get_pos()] = float("inf")
prev[square.get_pos()] = None
if square.state in [SquareState.EMPTY, SquareState.START, SquareState.END]:
q.append(pos)
dist[start_pos] = 0
while q:
u = min(q, key=dist.__getitem__)
q.remove(u)
for v in _get_valid_neighbours(*u):
alt = dist[u] + 1
if alt < dist[v]:
dist[v] = alt
prev[v] = u
vr, vc = v
grid[vr][vc].change_state(SquareState.VISITED)
if v == end_pos:
q = list()
break
picasso.draw(WINDOW, grid)
for event in pygame.event.get():
if event.type == pygame.QUIT:
finished = True
q = list()
break
path = _reconstruct_path()
for square in path:
row, col = square
grid[row][col].change_state(SquareState.PATH)
picasso.draw(WINDOW, grid)
for event in pygame.event.get():
if event.type == pygame.QUIT:
finished = True
break
print(f'Path found, took {len(path)} moves')
print(f'Moves: {path}')
print()
pygame.quit()
if __name__ == '__main__':
DijkstraPathfinder.find_path()
I Have tried to change this up, especially the last prints but it seems that it still does the same thing, where it only shows that "Path found, took 1 moves" and then below it shows "Moves: end_pos" where end_pos is wherever you had placed your final point.
In your implementation where you iterate over the neighbours:
for v in _get_valid_neighbours(*u)
You don't append anything to q, so the iteration stops there. As a result, in _reconstruct_path(), there is no prev node for the end point, and you get the path length as one.
I'm trying to create a collision detection between 4 controllable characters on an RPG battle map. Here is the function I'm using
def player_collission(Lord_x,Lord_y,Journeyman_x,Journeyman_y,Archer_x,Archer_y,
Cleric_x,Cleric_y):
print("Running")
if abs(Lord_x - Journeyman_x) <= 0 and abs(Lord_y - Journeyman_y) <= 0:
print("Colission detected")
return True
elif abs(Lord_x - Archer_x) <= 0 and abs(Lord_y - Archer_y) <= 0:
print("Colission detected")
return True
elif abs(Lord_x - Cleric_x) <= 0 and abs(Lord_y == Cleric_y) <= 0:
print("Colission detected")
return True
elif abs(Journeyman_x - Archer_x) <= 0 and abs(Journeyman_y - Archer_y) <= 0:
print("Colission detected")
return True
elif abs(Journeyman_x - Cleric_x) <= 0 and abs(Journeyman_y - Cleric_y) <= 0:
print("Colission detected")
return True
elif abs(Archer_x - Cleric_x) <= 0 and abs(Archer_y == Cleric_y) <= 0:
print("Colission detected")
return True
else:
return False #I didnt use classes so it has alot of if statements
if player_up:
p_collide = player_collission(Lord_x,Lord_y,Journeyman_x,Journeyman_y,Archer_x,Archer_y,
Cleric_x,Cleric_y)
if current_player == "lord":
if p_collide != True:
Lord_y -= tile_increment
if Lord_y <= 0:
Lord_y = 50
What happens is that the characters still move into each other but it detects the collision after it has already moved into each other and freezes all movement. I'm not sure how to re arrange it to make it work properly.
You detect collision when it has already happened. This is why you see characters overlapping.
Instead, you should detect if a collision is going to happen, an prevent a motion that would lead to that.
An example:
def move(coords, velocity):
"""Moves coords according to velocity."""
x, y = coords # Unpack a 2-tuple.
vx, vy = velocity
return (x + vx, y + vy)
tom_coords = (0, 0) # Tom is in the corner.
tom_v = (1, 1) # Tom moves by diagonal.
jerry_coords = (5, 0) # Jerry is a bit away from Tom.
jerry_v = (0, 1) # Jerry moves vertically.
while True:
new_tom_coords = move(tom_coords, tom_v) # Tom moves without fear.
new_jerry_coords = move(jerry_coords, jerry_v)
if new_jerry_coords == new_tom_coords: # Would be a collision!
new_jerry_coords = jerry_coords # Back to previous tile.
vx, vy = jerry_v
jerry_v = (-vx, -vy) # Jerry runs back.
print("Collision imminent, Jerry runs away!")
else:
jerry_coords = new_jerry_coords # Only update if no collision.
# Could also check collisions with walls, etc.
tom_coords = new_tom_coords
# Not inside pygame, so just print it and wait for a key press.
print('Tom:', tom_coords, 'Jerry:', jerry_coords)
input("Enter to continue, Ctrl+C to stop ")
Run it in and see how Tom and Jerry come close to each other but never occupy the same tile.
I'm doing a mini-project on Coursera and I can run most parts of my code. However there's an error in the critical part about the game's match or not checking.
# implementation of card game - Memory
import simplegui
import random
# helper function to initialize globals
def new_game():
global turns, state, pairs, cards
turns = 0
state = 0
pairs = []
cards = range(9) * 2
random.shuffle(cards)
# define event handlers
def mouseclick(pos):
# add game state logic here
global turns, state, pairs
pointed = pos[0] // 50
if pointed in pairs:
pass
else:
if state == 0:
state = 1
pairs.append(pointed)
elif state == 1:
state = 2
turns += 1
label.set_text('Turns =' + str(turns))
pairs.append(pointed)
# if cards[pairs[-2]] == cards[[pairs[-1]]:
# flag = True
# else:
# flag = False
else:
state = 1
if flag == False:
del pairs[-2:]
pairs.append(pointed)
# cards are logically 50x100 pixels in size
def draw(canvas):
for n in range(1, 16):
canvas.draw_line((n * 50, 0), (n * 50, 100), 1, 'Green')
for n in pairs:
canvas.draw_line((n * 50 + 25, 0), (n * 50 + 25, 100), 50, 'White')
for n in pairs:
canvas.draw_text(str(cards[n]), (n * 50 + 15, 65), 50, 'Black')
# create frame and add a button and labels
frame = simplegui.create_frame("Memory", 800, 100)
frame.set_canvas_background('Red')
frame.add_button("Reset", new_game)
label = frame.add_label("Turns = 0")
# register event handlers
frame.set_mouseclick_handler(mouseclick)
frame.set_draw_handler(draw)
# get things rolling
new_game()
frame.start()
# Always remember to review the grading rubric
I commented out Line 31 to 34 and that's the part where I have a problem. The console keeps telling me Line 31: SyntaxError: bad input (' ') but I think the indentation is correctly made.
Please help me figure out why it's a 'bad input', thanks a lot!
Update:
Thanks to Russell's help, this function works now.
# define event handlers
def mouseclick(pos):
# add game state logic here
global turns, state, pairs, flag
pointed = pos[0] // 50
if pointed in pairs:
pass
else:
if state == 0:
state = 1
pairs.append(pointed)
elif state == 1:
state = 2
turns += 1
label.set_text('Turns =' + str(turns))
pairs.append(pointed)
if cards[pairs[-2]] == cards[pairs[-1]]:
flag = True
else:
flag = False
else:
state = 1
if flag == False:
del pairs[-2:]
pairs.append(pointed)
Your if statement is indented too far.
elif state == 1:
state = 2
turns += 1
label.set_text('Turns =' + str(turns))
pairs.append(pointed)
if cards[pairs[-2]] == cards[pairs[-1]]:
flag = True
else:
flag = False
else:
state = 1
if flag == False:
del pairs[-2:]
pairs.append(pointed)
I am currently working on my Python game, in ika, which uses python 2.5
I decided to use A* pathfinding for the AI. However, I find it too slow for my needs (3-4 enemies can lag the game, but I would like to supply up to 4-5 without problems). I know, that such complex search like A* is not mean to be scripted in python, but I am pretty sure, that my pathfinder is also implemented in the wrong way.
My question is: How can I speed up this algorithm?
I wrote my own binary heap, and there are some try: except: lines inside some functions. Those lines can create large overhead? Are there better methods maintaining the open list?
I supplied the algorithm with graphics interface, for testing purposes (when the pathfinder finishes searching, it will write the number of iterations and seconds it takes to find the path, inside the ika.txt file. Also, Pressing A will do a complete search, and S does that step by step.)
Graphical version:
http://data.hu/get/6084681/A_star.rar
Also, here is a pastebin version:
http://pastebin.com/9N8ybX5F
Here is the main code I use for pathfinding:
import ika
import time
class Node:
def __init__(self,x,y,parent=None,g=0,h=0):
self.x = x
self.y = y
self.parent = parent
self.g = g
self.h = h
def cost(self):
return self.g + self.h
def equal(self,node):
if self.x == node.x and self.y == node.y:
return True
else:
return False
class Emerald_Pathfinder:
def __init__(self):
pass
def setup(self,start,goal):
self.start = start
self.goal = goal
self.openlist = [None,start] # Implemented as binary heap
self.closedlist = {} # Implemented as hash
self.onopenlist = {} # Hash, for searching the openlist
self.found = False
self.current = None
self.iterations = 0
def lowest_cost(self):
pass
def add_nodes(self,current):
nodes = []
x = current.x
y = current.y
self.add_node(x+1,y,current,10,nodes)
self.add_node(x-1,y,current,10,nodes)
self.add_node(x,y+1,current,10,nodes)
self.add_node(x,y-1,current,10,nodes)
# Dont cut across corners
up = map.is_obstacle((x,y-1),x,y-1)
down = map.is_obstacle((x,y+1),x,y+1)
left = map.is_obstacle((x-1,y),x-1,y)
right = map.is_obstacle((x+1,y),x+1,y)
if right == False and down == False:
self.add_node(x+1,y+1,current,14,nodes)
if left == False and up == False:
self.add_node(x-1,y-1,current,14,nodes)
if right == False and up == False:
self.add_node(x+1,y-1,current,14,nodes)
if left == False and down == False:
self.add_node(x-1,y+1,current,14,nodes)
return nodes
def heuristic(self,x1,y1,x2,y2):
return (abs(x1-x2)+abs(y1-y2))*10
def add_node(self,x,y,parent,cost,list):
# If not obstructed
if map.is_obstacle((x,y),x,y) == False:
g = parent.g + cost
h = self.heuristic(x,y,self.goal.x,self.goal.y)
node = Node(x,y,parent,g,h)
list.append(node)
def ignore(self,node,current):
# If its on the closed list, or open list, ignore
try:
if self.closedlist[(node.x,node.y)] == True:
return True
except:
pass
# If the node is on the openlist, do the following
try:
# If its on the open list
if self.onopenlist[(node.x,node.y)] != None:
# Get the id number of the item on the real open list
index = self.openlist.index(self.onopenlist[(node.x,node.y)])
# If one of the coordinates equal, its not diagonal.
if node.x == current.x or node.y == current.y:
cost = 10
else:
cost = 14
# Check, is this items G cost is higher, than the current G + cost
if self.openlist[index].g > (current.g + cost):
# If so, then, make the list items parent, the current node.
self.openlist[index].g = current.g + cost
self.openlist[index].parent = current
# Now resort the binary heap, in the right order.
self.resort_binary_heap(index)
# And ignore the node
return True
except:
pass
return False
def resort_binary_heap(self,index):
m = index
while m > 1:
if self.openlist[m/2].cost() > self.openlist[m].cost():
temp = self.openlist[m/2]
self.openlist[m/2] = self.openlist[m]
self.openlist[m] = temp
m = m / 2
else:
break
def heap_add(self,node):
self.openlist.append(node)
# Add item to the onopenlist.
self.onopenlist[(node.x,node.y)] = node
m = len(self.openlist)-1
while m > 1:
if self.openlist[m/2].cost() > self.openlist[m].cost():
temp = self.openlist[m/2]
self.openlist[m/2] = self.openlist[m]
self.openlist[m] = temp
m = m / 2
else:
break
def heap_remove(self):
if len(self.openlist) == 1:
return
first = self.openlist[1]
# Remove the first item from the onopenlist
self.onopenlist[(self.openlist[1].x,self.openlist[1].y)] = None
last = self.openlist.pop(len(self.openlist)-1)
if len(self.openlist) == 1:
return last
else:
self.openlist[1] = last
v = 1
while True:
u = v
# If there is two children
if (2*u)+1 < len(self.openlist):
if self.openlist[2*u].cost() <= self.openlist[u].cost():
v = 2*u
if self.openlist[(2*u)+1].cost() <= self.openlist[v].cost():
v = (2*u)+1
# If there is only one children
elif 2*u < len(self.openlist):
if self.openlist[2*u].cost() <= self.openlist[u].cost():
v = 2*u
# If at least one child is smaller, than parent, swap them
if u != v:
temp = self.openlist[u]
self.openlist[u] = self.openlist[v]
self.openlist[v] = temp
else:
break
return first
def iterate(self):
# If the open list is empty, exit the game
if len(self.openlist) == 1:
ika.Exit("no path found")
# Expand iteration by one
self.iterations += 1
# Make the current node the lowest cost
self.current = self.heap_remove()
# Add it to the closed list
self.closedlist[(self.current.x,self.current.y)] = True
# Are we there yet?
if self.current.equal(self.goal) == True:
# Target reached
self.goal = self.current
self.found = True
print self.iterations
else:
# Add the adjacent nodes, and check them
nodes_around = self.add_nodes(self.current)
for na in nodes_around:
if self.ignore(na,self.current) == False:
self.heap_add(na)
def iterateloop(self):
time1 = time.clock()
while 1:
# If the open list is empty, exit the game
if len(self.openlist) == 1:
ika.Exit("no path found")
# Expand iteration by one
self.iterations += 1
# Make the current node the lowest cost
self.current = self.heap_remove()
# Add it to the closed list
self.closedlist[(self.current.x,self.current.y)] = True
# Are we there yet?
if self.current.equal(self.goal) == True:
# Target reached
self.goal = self.current
self.found = True
print "Number of iterations"
print self.iterations
break
else:
# Add the adjacent nodes, and check them
nodes_around = self.add_nodes(self.current)
for na in nodes_around:
if self.ignore(na,self.current) == False:
self.heap_add(na)
time2 = time.clock()
time3 = time2-time1
print "Seconds to find path:"
print time3
class Map:
def __init__(self):
self.map_size_x = 20
self.map_size_y = 15
self.obstructed = {} # Library, containing x,y couples
self.start = [2*40,3*40]
self.unit = [16*40,8*40]
def is_obstacle(self,couple,x,y):
if (x >= self.map_size_x or x < 0) or (y >= self.map_size_y or y < 0):
return True
try:
if self.obstructed[(couple)] != None:
return True
except:
return False
def render_screen():
# Draw the Character
ika.Video.DrawRect(map.start[0],map.start[1],map.start[0]+40,map.start[1]+40,ika.RGB(40,200,10),1)
# Draw walls
for x in range(0,map.map_size_x):
for y in range(0,map.map_size_y):
if map.is_obstacle((x,y),x,y) == True:
ika.Video.DrawRect(x*40,y*40,(x*40)+40,(y*40)+40,ika.RGB(168,44,0),1)
# Draw openlist items
for node in path.openlist:
if node == None:
continue
x = node.x
y = node.y
ika.Video.DrawRect(x*40,y*40,(x*40)+40,(y*40)+40,ika.RGB(100,100,100,50),1)
# Draw closedlist items
for x in range(0,map.map_size_x):
for y in range(0,map.map_size_y):
try:
if path.closedlist[(x,y)] == True:
ika.Video.DrawRect(x*40,y*40,(x*40)+20,(y*40)+20,ika.RGB(0,0,255))
except:
pass
# Draw the current square
try:
ika.Video.DrawRect(path.current.x*40,path.current.y*40,(path.current.x*40)+40,(path.current.y*40)+40,ika.RGB(128,128,128), 1)
except:
pass
ika.Video.DrawRect(mouse_x.Position(),mouse_y.Position(),mouse_x.Position()+8,mouse_y.Position()+8,ika.RGB(128,128,128), 1)
# Draw the path, if reached
if path.found == True:
node = path.goal
while node.parent:
ika.Video.DrawRect(node.x*40,node.y*40,(node.x*40)+40,(node.y*40)+40,ika.RGB(40,200,200),1)
node = node.parent
# Draw the Target
ika.Video.DrawRect(map.unit[0],map.unit[1],map.unit[0]+40,map.unit[1]+40,ika.RGB(128,40,200),1)
def mainloop():
while 1:
render_screen()
if mouse_middle.Pressed():
# Iterate pathfinder
if path.found == False:
path.iterateloop()
elif mouse_right.Pressed():
# Iterate pathfinder by one
if path.found == False:
path.iterate()
elif ika.Input.keyboard["A"].Pressed():
# Iterate pathfinder
if path.found == False:
path.iterateloop()
elif ika.Input.keyboard["S"].Pressed():
# Iterate pathfinder by one
if path.found == False:
path.iterate()
elif mouse_left.Position():
# Add a square to the map, to be obstructed
if path.iterations == 0:
x = mouse_x.Position()
y = mouse_y.Position()
map.obstructed[(int(x/40),int(y/40))] = True
# Mouse preview
x = mouse_x.Position()
y = mouse_y.Position()
mx = int(x/40)*40
my = int(y/40)*40
ika.Video.DrawRect(mx,my,mx+40,my+40,ika.RGB(150,150,150,70),1)
ika.Video.ShowPage()
ika.Input.Update()
map = Map()
path = Emerald_Pathfinder()
path.setup(Node(map.start[0]/40,map.start[1]/40),Node(map.unit[0]/40,map.unit[1]/40))
mouse_middle = ika.Input.mouse.middle
mouse_right = ika.Input.mouse.right
mouse_left = ika.Input.mouse.left
mouse_x = ika.Input.mouse.x
mouse_y = ika.Input.mouse.y
# Initialize loop
mainloop()
I appreciate any help!
(sorry for any spelling mistakes, English is not my native language)
I think a proper implementation in python will be fast enough for your purposes. But the boost library has an astar implementation and python bindings. https://github.com/erwinvaneijk/bgl-python