From ac00c08ed49670d694ba822092cc3ac59c54961a Mon Sep 17 00:00:00 2001
From: "Egli Adrian (IT-SCI-API-PFI)" <adrian.egli@sbb.ch>
Date: Wed, 18 Sep 2019 12:13:51 +0200
Subject: [PATCH] chebyshev distance added
---
.../simple_example_city_railway_generator.py | 9 ++++++---
flatland/core/grid/grid_utils.py | 16 ++++++++++++++++
2 files changed, 22 insertions(+), 3 deletions(-)
diff --git a/examples/simple_example_city_railway_generator.py b/examples/simple_example_city_railway_generator.py
index 14de854a..98156c6a 100644
--- a/examples/simple_example_city_railway_generator.py
+++ b/examples/simple_example_city_railway_generator.py
@@ -17,9 +17,12 @@ if os.path.exists("./../render_output/"):
np.random.seed(itrials)
# select distance function used in a-star path finding
- dist_fun = Vec2d.get_euclidean_distance
- if np.random.choice(1) == 0:
- dist_fun = Vec2d.get_manhattan_distance
+ dist_fun = Vec2d.get_manhattan_distance
+ dfsel = itrials % 3
+ if dfsel == 1:
+ dist_fun = Vec2d.get_euclidean_distance
+ elif dfsel == 2:
+ dist_fun = Vec2d.get_chebyshev_distance
# create RailEnv and use the city_generator to create a map
env = RailEnv(width=40 + np.random.choice(100),
diff --git a/flatland/core/grid/grid_utils.py b/flatland/core/grid/grid_utils.py
index 3fda39b1..47cbb944 100644
--- a/flatland/core/grid/grid_utils.py
+++ b/flatland/core/grid/grid_utils.py
@@ -71,6 +71,7 @@ class Vec2dOperations:
def get_norm(node: Vector2D) -> float:
"""
calculates the euclidean norm of the 2d vector
+ [see: https://lyfat.wordpress.com/2012/05/22/euclidean-vs-chebyshev-vs-manhattan-distance/]
:param node: tuple with coordinate (x,y) or 2d vector
:return:
@@ -95,6 +96,7 @@ class Vec2dOperations:
def get_manhattan_distance(node_a: Vector2D, node_b: Vector2D) -> float:
"""
calculates the manhattan distance of the 2d vector
+ [see: https://lyfat.wordpress.com/2012/05/22/euclidean-vs-chebyshev-vs-manhattan-distance/]
:param node: tuple with coordinate (x,y) or 2d vector
:return:
@@ -104,6 +106,20 @@ class Vec2dOperations:
delta = (Vec2dOperations.subtract(node_b, node_a))
return np.abs(delta[0]) + np.abs(delta[1])
+ @staticmethod
+ def get_chebyshev_distance(node_a: Vector2D, node_b: Vector2D) -> float:
+ """
+ calculates the chebyshev norm of the 2d vector
+ [see: https://lyfat.wordpress.com/2012/05/22/euclidean-vs-chebyshev-vs-manhattan-distance/]
+
+ :param node: tuple with coordinate (x,y) or 2d vector
+ :return:
+ -------
+ returns the chebyshev distance
+ """
+ delta = (Vec2dOperations.subtract(node_b, node_a))
+ return max(np.abs(delta[0]), np.abs(delta[1]))
+
@staticmethod
def normalize(node: Vector2D) -> Tuple[float, float]:
"""
--
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