From bf9d34d1a30c05b9119815bf10f55f316873e848 Mon Sep 17 00:00:00 2001
From: Dustin Carlino <dabreegster@gmail.com>
Date: Sat, 21 Nov 2020 10:12:29 -0800
Subject: [PATCH] Drop results farther than 15 minutes away. #393

It'd be more efficient to terminate the Dijkstra's search directly, but
petgraph doesn't have an option for that, so we'll have to implement
Dijkstra's manually (shouldn't be hard).
---
 game/src/devtools/fifteen_min/isochrone.rs |  4 +++-
 map_model/src/connectivity.rs              | 13 ++++++++++---
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/game/src/devtools/fifteen_min/isochrone.rs b/game/src/devtools/fifteen_min/isochrone.rs
index a4a8e8e935..b6bf6afdf3 100644
--- a/game/src/devtools/fifteen_min/isochrone.rs
+++ b/game/src/devtools/fifteen_min/isochrone.rs
@@ -28,7 +28,9 @@ impl Isochrone {
         );
 
         // Calculate the cost from the start building to every other building in the map
-        for (b, cost) in connectivity::all_costs_from(&app.primary.map, start) {
+        for (b, cost) in
+            connectivity::all_costs_from(&app.primary.map, start, Duration::minutes(15))
+        {
             // What grid cell does the building belong to?
             let pt = app.primary.map.get_b(b).polygon.center();
             let idx = grid.idx(
diff --git a/map_model/src/connectivity.rs b/map_model/src/connectivity.rs
index 3a27851848..00d526c145 100644
--- a/map_model/src/connectivity.rs
+++ b/map_model/src/connectivity.rs
@@ -47,8 +47,12 @@ pub fn find_scc(map: &Map, constraints: PathConstraints) -> (HashSet<LaneID>, Ha
 }
 
 /// Starting from one building, calculate the cost to all others. If a destination isn't reachable,
-/// it won't be included in the results.
-pub fn all_costs_from(map: &Map, start: BuildingID) -> HashMap<BuildingID, Duration> {
+/// it won't be included in the results. Ignore results greater than the time_limit away.
+pub fn all_costs_from(
+    map: &Map,
+    start: BuildingID,
+    time_limit: Duration,
+) -> HashMap<BuildingID, Duration> {
     // TODO This is hardcoded to walking; take a PathConstraints.
     let graph = build_graph_for_pedestrians(map);
     let start = WalkingNode::closest(map.get_b(start).sidewalk_pos, map);
@@ -60,7 +64,10 @@ pub fn all_costs_from(map: &Map, start: BuildingID) -> HashMap<BuildingID, Durat
     let mut results = HashMap::new();
     for b in map.all_buildings() {
         if let Some(seconds) = cost_per_node.get(&WalkingNode::closest(b.sidewalk_pos, map)) {
-            results.insert(b.id, Duration::seconds(*seconds as f64));
+            let duration = Duration::seconds(*seconds as f64);
+            if duration <= time_limit {
+                results.insert(b.id, duration);
+            }
         }
     }
     results