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[mypy] fix type annotations for graphs/a_star.py #4052 (#5224)

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* [mypy] fix type annotations for graphs/a_star.py #4052

* updating DIRECTORY.md

* Add from __future__ import anotations

* rename delta by DIRECTIONS

Co-authored-by: John Law <johnlaw.po@gmail.com>

* Rename delta by DIRECTIONS in all code

* Enclose script in __main__ code block

* Refactor DIRECTIONS with comments for readibility

* Delete heuristic example comment

* Do not print, return all values

* Fix multilines

* fix black

* Update a_star.py

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Co-authored-by: John Law <johnlaw.po@gmail.com>
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poloso 2021-10-22 05:07:28 -05:00 committed by GitHub
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commit 061614880d
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1 changed files with 50 additions and 42 deletions
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92
graphs/a_star.py
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@ -1,37 +1,21 @@
grid = [
[0, 1, 0, 0, 0, 0],
[0, 1, 0, 0, 0, 0], # 0 are free path whereas 1's are obstacles
[0, 1, 0, 0, 0, 0],
[0, 1, 0, 0, 1, 0],
[0, 0, 0, 0, 1, 0],
from __future__ import annotations
DIRECTIONS = [
[-1, 0], # left
[0, -1], # down
[1, 0], # right
[0, 1], # up
]
"""
heuristic = [[9, 8, 7, 6, 5, 4],
[8, 7, 6, 5, 4, 3],
[7, 6, 5, 4, 3, 2],
[6, 5, 4, 3, 2, 1],
[5, 4, 3, 2, 1, 0]]"""
init = [0, 0]
goal = [len(grid) - 1, len(grid[0]) - 1] # all coordinates are given in format [y,x]
cost = 1
# the cost map which pushes the path closer to the goal
heuristic = [[0 for row in range(len(grid[0]))] for col in range(len(grid))]
for i in range(len(grid)):
for j in range(len(grid[0])):
heuristic[i][j] = abs(i - goal[0]) + abs(j - goal[1])
if grid[i][j] == 1:
heuristic[i][j] = 99 # added extra penalty in the heuristic map
# the actions we can take
delta = [[-1, 0], [0, -1], [1, 0], [0, 1]] # go up # go left # go down # go right
# function to search the path
def search(grid, init, goal, cost, heuristic):
def search(
grid: list[list[int]],
init: list[int],
goal: list[int],
cost: int,
heuristic: list[list[int]],
) -> tuple[list[list[int]], list[list[int]]]:
closed = [
[0 for col in range(len(grid[0]))] for row in range(len(grid))
@ -52,7 +36,7 @@ def search(grid, init, goal, cost, heuristic):
while not found and not resign:
if len(cell) == 0:
return "FAIL"
raise ValueError("Algorithm is unable to find solution")
else: # to choose the least costliest action so as to move closer to the goal
cell.sort()
cell.reverse()
@ -64,9 +48,9 @@ def search(grid, init, goal, cost, heuristic):
if x == goal[0] and y == goal[1]:
found = True
else:
for i in range(len(delta)): # to try out different valid actions
x2 = x + delta[i][0]
y2 = y + delta[i][1]
for i in range(len(DIRECTIONS)): # to try out different valid actions
x2 = x + DIRECTIONS[i][0]
y2 = y + DIRECTIONS[i][1]
if x2 >= 0 and x2 < len(grid) and y2 >= 0 and y2 < len(grid[0]):
if closed[x2][y2] == 0 and grid[x2][y2] == 0:
g2 = g + cost
@ -79,8 +63,8 @@ def search(grid, init, goal, cost, heuristic):
y = goal[1]
invpath.append([x, y]) # we get the reverse path from here
while x != init[0] or y != init[1]:
x2 = x - delta[action[x][y]][0]
y2 = y - delta[action[x][y]][1]
x2 = x - DIRECTIONS[action[x][y]][0]
y2 = y - DIRECTIONS[action[x][y]][1]
x = x2
y = y2
invpath.append([x, y])
@ -88,13 +72,37 @@ def search(grid, init, goal, cost, heuristic):
path = []
for i in range(len(invpath)):
path.append(invpath[len(invpath) - 1 - i])
return path, action
if __name__ == "__main__":
grid = [
[0, 1, 0, 0, 0, 0],
[0, 1, 0, 0, 0, 0], # 0 are free path whereas 1's are obstacles
[0, 1, 0, 0, 0, 0],
[0, 1, 0, 0, 1, 0],
[0, 0, 0, 0, 1, 0],
]
init = [0, 0]
# all coordinates are given in format [y,x]
goal = [len(grid) - 1, len(grid[0]) - 1]
cost = 1
# the cost map which pushes the path closer to the goal
heuristic = [[0 for row in range(len(grid[0]))] for col in range(len(grid))]
for i in range(len(grid)):
for j in range(len(grid[0])):
heuristic[i][j] = abs(i - goal[0]) + abs(j - goal[1])
if grid[i][j] == 1:
# added extra penalty in the heuristic map
heuristic[i][j] = 99
path, action = search(grid, init, goal, cost, heuristic)
print("ACTION MAP")
for i in range(len(action)):
print(action[i])
return path
a = search(grid, init, goal, cost, heuristic)
for i in range(len(a)):
print(a[i])
for i in range(len(path)):
print(path[i])