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Fix greedy_best_first (#8775)
* fix: typo #8770 * refactor: delete unnecessary continue * add test grids * fix: add \_\_eq\_\_ in Node class #8770 * fix: delete unnecessary code - node in self.open_nodes is always better node #8770 * fix: docstring * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci * fix: docstring max length * refactor: get the successors using a list comprehension * Apply suggestions from code review --------- Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com> Co-authored-by: Tianyi Zheng <tianyizheng02@gmail.com>
This commit is contained in:
Juyoung Kim
GitHub
parent
490e645ed3
commit
cecf1fdd52
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@ -6,14 +6,32 @@ from __future__ import annotations
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Path = list[tuple[int, int]]
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grid = [
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# 0's are free path whereas 1's are obstacles
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TEST_GRIDS = [
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[
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[0, 0, 0, 0, 0, 0, 0],
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[0, 1, 0, 0, 0, 0, 0], # 0 are free path whereas 1's are obstacles
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[0, 1, 0, 0, 0, 0, 0],
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[0, 0, 0, 0, 0, 0, 0],
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[0, 0, 1, 0, 0, 0, 0],
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[1, 0, 1, 0, 0, 0, 0],
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[0, 0, 0, 0, 0, 0, 0],
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[0, 0, 0, 0, 1, 0, 0],
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],
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[
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[0, 0, 0, 1, 1, 0, 0],
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[0, 0, 0, 0, 1, 0, 1],
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[0, 0, 0, 1, 1, 0, 0],
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[0, 1, 0, 0, 1, 0, 0],
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[1, 0, 0, 1, 1, 0, 1],
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[0, 0, 0, 0, 0, 0, 0],
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],
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[
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[0, 0, 1, 0, 0],
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[0, 1, 0, 0, 0],
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[0, 0, 1, 0, 1],
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[1, 0, 0, 1, 1],
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[0, 0, 0, 0, 0],
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],
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]
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delta = ([-1, 0], [0, -1], [1, 0], [0, 1]) # up, left, down, right
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@ -65,10 +83,14 @@ class Node:
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def __lt__(self, other) -> bool:
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return self.f_cost < other.f_cost
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def __eq__(self, other) -> bool:
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return self.pos == other.pos
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class GreedyBestFirst:
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"""
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>>> gbf = GreedyBestFirst((0, 0), (len(grid) - 1, len(grid[0]) - 1))
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>>> grid = TEST_GRIDS[2]
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>>> gbf = GreedyBestFirst(grid, (0, 0), (len(grid) - 1, len(grid[0]) - 1))
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>>> [x.pos for x in gbf.get_successors(gbf.start)]
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[(1, 0), (0, 1)]
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>>> (gbf.start.pos_y + delta[3][0], gbf.start.pos_x + delta[3][1])
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@ -78,11 +100,14 @@ class GreedyBestFirst:
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>>> gbf.retrace_path(gbf.start)
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[(0, 0)]
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>>> gbf.search() # doctest: +NORMALIZE_WHITESPACE
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[(0, 0), (1, 0), (2, 0), (3, 0), (3, 1), (4, 1), (5, 1), (6, 1),
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(6, 2), (6, 3), (5, 3), (5, 4), (5, 5), (6, 5), (6, 6)]
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[(0, 0), (1, 0), (2, 0), (2, 1), (3, 1), (4, 1), (4, 2), (4, 3),
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(4, 4)]
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"""
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def __init__(self, start: tuple[int, int], goal: tuple[int, int]):
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def __init__(
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self, grid: list[list[int]], start: tuple[int, int], goal: tuple[int, int]
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):
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self.grid = grid
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self.start = Node(start[1], start[0], goal[1], goal[0], 0, None)
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self.target = Node(goal[1], goal[0], goal[1], goal[0], 99999, None)
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@ -114,14 +139,6 @@ class GreedyBestFirst:
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if child_node not in self.open_nodes:
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self.open_nodes.append(child_node)
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else:
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# retrieve the best current path
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better_node = self.open_nodes.pop(self.open_nodes.index(child_node))
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if child_node.g_cost < better_node.g_cost:
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self.open_nodes.append(child_node)
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else:
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self.open_nodes.append(better_node)
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if not self.reached:
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return [self.start.pos]
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@ -131,28 +148,22 @@ class GreedyBestFirst:
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"""
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Returns a list of successors (both in the grid and free spaces)
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"""
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successors = []
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for action in delta:
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pos_x = parent.pos_x + action[1]
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pos_y = parent.pos_y + action[0]
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if not (0 <= pos_x <= len(grid[0]) - 1 and 0 <= pos_y <= len(grid) - 1):
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continue
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if grid[pos_y][pos_x] != 0:
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continue
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successors.append(
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return [
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Node(
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pos_x,
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pos_y,
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self.target.pos_y,
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self.target.pos_x,
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self.target.pos_y,
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parent.g_cost + 1,
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parent,
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)
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for action in delta
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if (
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0 <= (pos_x := parent.pos_x + action[1]) < len(self.grid[0])
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and 0 <= (pos_y := parent.pos_y + action[0]) < len(self.grid)
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and self.grid[pos_y][pos_x] == 0
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)
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return successors
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]
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def retrace_path(self, node: Node | None) -> Path:
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"""
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@ -168,6 +179,9 @@ class GreedyBestFirst:
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if __name__ == "__main__":
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for idx, grid in enumerate(TEST_GRIDS):
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print(f"==grid-{idx + 1}==")
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init = (0, 0)
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goal = (len(grid) - 1, len(grid[0]) - 1)
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for elem in grid:
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@ -175,7 +189,7 @@ if __name__ == "__main__":
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print("------")
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greedy_bf = GreedyBestFirst(init, goal)
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greedy_bf = GreedyBestFirst(grid, init, goal)
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path = greedy_bf.search()
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if path:
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for pos_x, pos_y in path:
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