From 8fbecf3fec145bed81dd9c62eba011fa1de3b8d1 Mon Sep 17 00:00:00 2001
From: Erik Nygren <erik.nygren@sbb.ch>
Date: Sat, 5 Oct 2019 09:27:23 -0400
Subject: [PATCH] retry with grid_mode true if no solution can be found for
random distributed cities
---
flatland/envs/rail_generators.py | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/flatland/envs/rail_generators.py b/flatland/envs/rail_generators.py
index 7d79c564..3983bb0d 100644
--- a/flatland/envs/rail_generators.py
+++ b/flatland/envs/rail_generators.py
@@ -571,6 +571,17 @@ def sparse_rail_generator(max_num_cities: int = 5, grid_mode: bool = False, max_
# reduce num_cities if less were generated in random mode
num_cities = len(city_positions)
+
+ # Try with evenly distributed cities
+ if num_cities < 2:
+ city_positions, city_cells = _generate_evenly_distr_city_positions(max_num_cities, city_radius, width,
+ height)
+ num_cities = len(city_positions)
+
+ # Fail
+ if num_cities < 2:
+ warnings.warn("Initial parameters cannot generate valid railway")
+ return
# Set up connection points for all cities
inner_connection_points, outer_connection_points, connection_info, city_orientations = _generate_city_connection_points(
city_positions, city_radius, rails_between_cities,
--
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