jan.mrna/pathfinding_demo
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Fixed swapped start/stop points

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Jan Mrna 2025-09-21 16:33:29 +02:00
parent 2145ac50a0
commit 5f517c6707
1 changed files with 27 additions and 24 deletions
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51
python/pathfinding_demo.py
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@ -265,9 +265,9 @@ class BFS(PathFinderBase):
def _CalculatePath(self, start_point: Point2D, end_point: Point2D) -> Optional[Path]: def _CalculatePath(self, start_point: Point2D, end_point: Point2D) -> Optional[Path]:
frontier: Queue[Point2D] = Queue() frontier: Queue[Point2D] = Queue()
frontier.put(end_point) # we start the computation from the end point frontier.put(start_point)
self._came_from: dict[Point2D, Optional[Point2D]] = { end_point: None } self._came_from: dict[Point2D, Optional[Point2D]] = { start_point: None }
self._distance: dict[Point2D, float] = { end_point: 0.0 } self._distance: dict[Point2D, float] = { start_point: 0.0 }
# build flow field # build flow field
early_exit = False early_exit = False
@ -279,17 +279,18 @@ class BFS(PathFinderBase):
self._distance[next_point] = self._distance[current] + 1.0 self._distance[next_point] = self._distance[current] + 1.0
_ = self._map.Visit(next_point) # visit only to track visited node count _ = self._map.Visit(next_point) # visit only to track visited node count
self._came_from[next_point] = current self._came_from[next_point] = current
if next_point == start_point: if next_point == end_point:
# early exit - if you want to build the whole flow field, remove this # early exit - if you want to build the whole flow field, remove this
early_exit = True early_exit = True
break break
# find actual path # find actual path
path: Path = [] path: Path = []
current = start_point current = end_point
path.append(current) path.append(current)
while self._came_from[current] is not None: while self._came_from[current] is not None:
current = self._came_from[current] current = self._came_from[current]
path.append(current) path.append(current)
path.reverse()
return path return path
@ -304,13 +305,13 @@ class DijkstraAlgorithm(PathFinderBase):
def _CalculatePath(self, start_point: Point2D, end_point: Point2D) -> Optional[Path]: def _CalculatePath(self, start_point: Point2D, end_point: Point2D) -> Optional[Path]:
frontier: PriorityQueue[PrioritizedItem] = PriorityQueue() frontier: PriorityQueue[PrioritizedItem] = PriorityQueue()
came_from: dict[Point2D, Optional[Point2D]] = {end_point: None} # we start from end node came_from: dict[Point2D, Optional[Point2D]] = {start_point: None}
cost_so_far: dict[Point2D, float] = {end_point: 0.0} cost_so_far: dict[Point2D, float] = {start_point: 0.0}
frontier.put(PrioritizedItem(end_point, 0.0)) frontier.put(PrioritizedItem(start_point, 0.0))
while not frontier.empty(): while not frontier.empty():
current = frontier.get().item current = frontier.get().item
if current == start_point: if current == end_point:
# early exit - remove if you want to build the whole flow map # early exit - remove if you want to build the whole flow map
break break
for next_point in self._map.GetNeighbours(current): for next_point in self._map.GetNeighbours(current):
@ -322,11 +323,12 @@ class DijkstraAlgorithm(PathFinderBase):
came_from[next_point] = current came_from[next_point] = current
# build the actual path # build the actual path
path: Path = [] path: Path = []
current = start_point current = end_point
path.append(current) path.append(current)
while came_from[current] is not None: while came_from[current] is not None:
current = came_from[current] current = came_from[current]
path.append(current) path.append(current)
path.reverse()
return path return path
@ -350,27 +352,27 @@ class GBFS(PathFinderBase):
def _CalculatePath(self, start_point: Point2D, end_point: Point2D) -> Optional[Path]: def _CalculatePath(self, start_point: Point2D, end_point: Point2D) -> Optional[Path]:
frontier: PriorityQueue[PrioritizedItem] = PriorityQueue() frontier: PriorityQueue[PrioritizedItem] = PriorityQueue()
came_from: dict[Point2D, Optional[Point2D]] = {end_point: None} came_from: dict[Point2D, Optional[Point2D]] = {start_point: None}
frontier.put(PrioritizedItem(end_point, 0.0)) # we start from the end frontier.put(PrioritizedItem(start_point, 0.0))
# create the flow field # create the flow field
while not frontier.empty(): while not frontier.empty():
current = frontier.get().item current = frontier.get().item
if current == start_point: if current == end_point:
# early exit # early exit
break break
for next_point in self._map.GetNeighbours(current): for next_point in self._map.GetNeighbours(current):
if next_point not in came_from: if next_point not in came_from:
priority = self.heuristic(start_point, next_point) priority = self.heuristic(end_point, next_point)
frontier.put(PrioritizedItem(next_point, priority)) frontier.put(PrioritizedItem(next_point, priority))
_ = self._map.Visit(next_point) # visit only to track visited node count _ = self._map.Visit(next_point) # visit only to track visited node count
came_from[next_point] = current came_from[next_point] = current
# create the actual path # create the actual path
path: Path = [start_point] path: Path = [end_point]
current = start_point
while came_from[current] is not None: while came_from[current] is not None:
current = came_from[current] current = came_from[current]
path.append(current) path.append(current)
path.reverse()
return path return path
@ -394,28 +396,29 @@ class A_star(PathFinderBase):
def _CalculatePath(self, start_point: Point2D, end_point: Point2D) -> Optional[Path]: def _CalculatePath(self, start_point: Point2D, end_point: Point2D) -> Optional[Path]:
frontier: PriorityQueue[PrioritizedItem] = PriorityQueue() frontier: PriorityQueue[PrioritizedItem] = PriorityQueue()
came_from: dict[Point2D, Optional[Point2D]] = { end_point: None } came_from: dict[Point2D, Optional[Point2D]] = { start_point: None }
cost_so_far: dict[Point2D, float] = { end_point: 0.0 } cost_so_far: dict[Point2D, float] = { start_point: 0.0 }
frontier.put(PrioritizedItem(end_point, 0.0)) frontier.put(PrioritizedItem(start_point, 0.0))
while not frontier.empty(): while not frontier.empty():
current = frontier.get().item current = frontier.get().item
if current == start_point: if current == end_point:
# early exit # early exit
break break
for next_point in self._map.GetNeighbours(current): for next_point in self._map.GetNeighbours(current):
new_cost = cost_so_far[current] + self._map.Visit(next_point) new_cost = cost_so_far[current] + self._map.Visit(next_point)
if next_point not in cost_so_far or new_cost < cost_so_far[next_point]: if next_point not in cost_so_far or new_cost < cost_so_far[next_point]:
cost_so_far[next_point] = new_cost cost_so_far[next_point] = new_cost
priority = new_cost + self.heuristic(start_point, next_point) priority = new_cost + self.heuristic(end_point, next_point)
frontier.put(PrioritizedItem(next_point, priority)) frontier.put(PrioritizedItem(next_point, priority))
came_from[next_point] = current came_from[next_point] = current
# create the actual path # create the actual path
path: Path = [start_point] path: Path = [end_point]
current = start_point current = end_point
while came_from[current] is not None: while came_from[current] is not None:
current = came_from[current] current = came_from[current]
path.append(current) path.append(current)
path.reverse()
return path return path
# #
@ -431,7 +434,7 @@ def main():
end_point: Point2D = Point2D((1,1)) end_point: Point2D = Point2D((1,1))
path_finder_classes: list[type[PathFinderBase]] = [ path_finder_classes: list[type[PathFinderBase]] = [
DFS, #DFS,
BFS, BFS,
DijkstraAlgorithm, DijkstraAlgorithm,
GBFS, GBFS,