3 # Any copyright is dedicated to the Public Domain.
4 # https://creativecommons.org/publicdomain/zero/1.0/
6 # Written by Francois Fleuret <francois@fleuret.org>
8 import torch, torchvision
10 ######################################################################
12 v_empty, v_wall, v_start, v_goal, v_path = 0, 1, 2, 3, 4
15 def create_maze(h=11, w=17, nb_walls=8):
21 m = torch.zeros(h, w, dtype=torch.int64)
31 int((r[1] * h).item()),
32 int((r[2] * h).item()),
33 int((r[3] * w).item()),
35 i1, i2, j = i1 - i1 % 2, i2 - i2 % 2, j - j % 2
36 i1, i2 = min(i1, i2), max(i1, i2)
37 if i2 - i1 > 1 and i2 - i1 <= h / 2 and m[i1 : i2 + 1, j].sum() <= 1:
42 int((r[1] * h).item()),
43 int((r[2] * w).item()),
44 int((r[3] * w).item()),
46 i, j1, j2 = i - i % 2, j1 - j1 % 2, j2 - j2 % 2
47 j1, j2 = min(j1, j2), max(j1, j2)
48 if j2 - j1 > 1 and j2 - j1 <= w / 2 and m[i, j1 : j2 + 1].sum() <= 1:
61 ######################################################################
64 def compute_distance(walls, i, j):
65 max_length = walls.numel()
66 dist = torch.full_like(walls, max_length)
69 pred_dist = torch.empty_like(dist)
76 dist[None, 1:-1, 0:-2],
79 dist[None, 0:-2, 1:-1],
86 dist[1:-1, 1:-1] = torch.min(dist[1:-1, 1:-1], d)
87 dist = walls * max_length + (1 - walls) * dist
89 if dist.equal(pred_dist):
90 return dist * (1 - walls)
93 ######################################################################
96 def compute_policy(walls, i, j):
97 distance = compute_distance(walls, i, j)
98 distance = distance + walls.numel() * walls
100 value = distance.new_full((4,) + distance.size(), walls.numel())
101 value[0, :, 1:] = distance[:, :-1]
102 value[1, :, :-1] = distance[:, 1:]
103 value[2, 1:, :] = distance[:-1, :]
104 value[3, :-1, :] = distance[1:, :]
106 proba = (value.min(dim=0)[0][None] == value).float()
107 proba = proba / proba.sum(dim=0)[None]
108 proba = proba * (1 - walls) + walls.float() / 4
113 ######################################################################
116 def mark_path(walls, i, j, goal_i, goal_j):
117 policy = compute_policy(walls, goal_i, goal_j)
118 action = torch.distributions.categorical.Categorical(
119 policy.permute(1, 2, 0)
122 n, nmax = 0, walls.numel()
123 while i != goal_i or j != goal_j:
124 di, dj = [(0, -1), (0, 1), (-1, 0), (1, 0)][action[i, j]]
125 i, j = i + di, j + dj
126 assert walls[i, j] == 0
132 def path_correctness(mazes, paths):
133 still_ok = (mazes - (paths * (paths < 4))).view(mazes.size(0), -1).abs().sum(1) == 0
134 reached = still_ok.new_zeros(still_ok.size())
135 current, pred_current = paths.clone(), paths.new_zeros(paths.size())
136 goal = (mazes == v_goal).long()
137 while not pred_current.equal(current):
138 pred_current.copy_(current)
139 u = (current == v_start).long()
141 u[:, 2:, 1:-1] + u[:, 0:-2, 1:-1] + u[:, 1:-1, 2:] + u[:, 1:-1, 0:-2] > 0
144 reached += ((goal[:, 1:-1, 1:-1] * possible_next).sum((1, 2)) == 1) * (
145 (current == v_path).sum((1, 2)) == 0
147 current[:, 1:-1, 1:-1] = (1 - u) * current[:, 1:-1, 1:-1] + (
149 ) * (possible_next * (current[:, 1:-1, 1:-1] == v_path))
150 still_ok *= (current == v_start).sum((1, 2)) <= 1
152 return still_ok * reached
155 ######################################################################
158 def create_maze_data(
159 nb, height=11, width=17, nb_walls=8, dist_min=10, progress_bar=lambda x: x
161 mazes = torch.empty(nb, height, width, dtype=torch.int64)
162 paths = torch.empty(nb, height, width, dtype=torch.int64)
164 for n in progress_bar(range(nb)):
165 maze = create_maze(height, width, nb_walls)
166 i = (1 - maze).nonzero()
168 start, goal = i[torch.randperm(i.size(0))[:2]]
169 if (start - goal).abs().sum() >= dist_min:
173 mark_path(path, start[0], start[1], goal[0], goal[1])
174 maze[start[0], start[1]] = v_start
175 maze[goal[0], goal[1]] = v_goal
176 path[start[0], start[1]] = v_start
177 path[goal[0], goal[1]] = v_goal
185 ######################################################################
188 def save_image(name, mazes, target_paths, predicted_paths=None, path_correct=None):
189 mazes, target_paths = mazes.cpu(), target_paths.cpu()
191 colors = torch.tensor(
193 [255, 255, 255], # empty
201 mazes = colors[mazes.reshape(-1)].reshape(mazes.size() + (-1,)).permute(0, 3, 1, 2)
203 colors[target_paths.reshape(-1)]
204 .reshape(target_paths.size() + (-1,))
207 imgs = torch.cat((mazes.unsqueeze(1), target_paths.unsqueeze(1)), 1)
209 if predicted_paths is not None:
210 predicted_paths = predicted_paths.cpu()
212 colors[predicted_paths.reshape(-1)]
213 .reshape(predicted_paths.size() + (-1,))
216 imgs = torch.cat((imgs, predicted_paths.unsqueeze(1)), 1)
219 if path_correct is None:
220 path_correct = torch.zeros(imgs.size(0)) <= 1
221 path_correct = path_correct.cpu().long().view(-1, 1, 1, 1)
222 img = torch.tensor([224, 224, 224]).view(1, -1, 1, 1) * path_correct + torch.tensor(
224 ).view(1, -1, 1, 1) * (1 - path_correct)
226 -1, -1, imgs.size(3) + 2, 1 + imgs.size(1) * (1 + imgs.size(4))
228 for k in range(imgs.size(1)):
232 1 : 1 + imgs.size(3),
233 1 + k * (1 + imgs.size(4)) : 1 + k * (1 + imgs.size(4)) + imgs.size(4),
236 img = img.float() / 255.0
238 torchvision.utils.save_image(img, name, nrow=4, padding=1, pad_value=224.0 / 256)
241 ######################################################################
243 if __name__ == "__main__":
245 device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
246 mazes, paths = create_maze_data(8)
247 mazes, paths = mazes.to(device), paths.to(device)
248 save_image("test.png", mazes, paths, paths)
249 print(path_correctness(mazes, paths))
251 ######################################################################