Speed up the 'find perfect home' tool by starting Dijkstra's floodfill with multiple sources. Only implemented for walking right now.

fifteen_min/src/find_home.rs

@@ -1,6 +1,6 @@
-use std::collections::{HashMap, HashSet};
+use std::collections::HashMap;
 
-use abstutil::{Counter, Parallelism, Timer};
+use abstutil::{prettyprint_usize, Counter, Parallelism, Timer};
 use geom::Percent;
 use map_gui::tools::PopupMsg;
 use map_model::{AmenityType, BuildingID};
@@ -89,33 +89,28 @@ fn score_houses(
     options: Options,
     timer: &mut Timer,
 ) -> HashMap<BuildingID, Percent> {
+    let num_categories = amenities.len();
     let mut satisfied_per_bldg: Counter<BuildingID> = Counter::new();
 
-    // There may be more clever ways to calculate this, but we'll take the brute-force approach of
-    // calculating the walkshed from every matching business.
-    let num_categories = amenities.len();
-    for category in amenities {
-        let mut stores: HashSet<BuildingID> = HashSet::new();
-        for b in app.map.all_buildings() {
-            if b.has_amenity(category) {
-                stores.insert(b.id);
-            }
-        }
-
-        let mut houses: HashSet<BuildingID> = HashSet::new();
     let map = &app.map;
     for times in timer.parallelize(
-            &format!("find houses close to {}", category),
+        "find houses close to amenities",
         Parallelism::Fastest,
-            stores.into_iter().collect(),
-            |b| options.clone().time_to_reach_building(map, b),
-        ) {
-            for (b, _) in times {
-                houses.insert(b);
+        amenities,
+        |category| {
+            // For each category, find all matching stores
+            let mut stores = Vec::new();
+            for b in map.all_buildings() {
+                if b.has_amenity(category) {
+                    stores.push(b.id);
                 }
             }
 
-        for b in houses {
+            // Then find all buildings reachable from any of those starting points
+            options.clone().times_from_buildings(map, stores)
+        },
+    ) {
+        for (b, _) in times {
             satisfied_per_bldg.inc(b);
         }
     }
@@ -140,12 +135,22 @@ impl Results {
         scores: HashMap<BuildingID, Percent>,
         amenities: Vec<AmenityType>,
     ) -> Box<dyn State<App>> {
+        // TODO Show imperfect matches with different colors.
+        let mut batch = GeomBatch::new();
+        let mut count = 0;
+        for (b, pct) in scores {
+            if pct == Percent::int(100) {
+                batch.push(Color::RED, app.map.get_b(b).polygon.clone());
+                count += 1;
+            }
+        }
+
         let panel = Panel::new(Widget::col(vec![
             Line("Results for your walkable home")
                 .small_heading()
                 .into_widget(ctx),
             // TODO Adjust text to say bikeshed, or otherwise reflect the options chosen
-            "Here are all of the matching houses.".text_widget(ctx),
+            format!("{} houses match", prettyprint_usize(count)).text_widget(ctx),
             format!(
                 "Containing at least 1 of each: {}",
                 amenities
@@ -164,14 +169,6 @@ impl Results {
         .aligned(HorizontalAlignment::RightInset, VerticalAlignment::TopInset)
         .build(ctx);
 
-        // TODO Show imperfect matches with different colors.
-        let mut batch = GeomBatch::new();
-        for (b, pct) in scores {
-            if pct == Percent::int(100) {
-                batch.push(Color::RED, app.map.get_b(b).polygon.clone());
-            }
-        }
-
         SimpleState::new(
             panel,
             Box::new(Results {

fifteen_min/src/isochrone.rs

@@ -38,18 +38,19 @@ pub enum Options {
 }
 
 impl Options {
-    pub fn time_to_reach_building(
+    // TODO doc
+    pub fn times_from_buildings(
         self,
         map: &Map,
-        start: BuildingID,
+        starts: Vec<BuildingID>,
     ) -> HashMap<BuildingID, Duration> {
         match self {
             Options::Walking(opts) => {
-                connectivity::all_walking_costs_from(map, start, Duration::minutes(15), opts)
+                connectivity::all_walking_costs_from(map, starts, Duration::minutes(15), opts)
             }
             Options::Biking => connectivity::all_vehicle_costs_from(
                 map,
-                start,
+                starts,
                 Duration::minutes(15),
                 PathConstraints::Bike,
             ),
@@ -59,7 +60,7 @@ impl Options {
 
 impl Isochrone {
     pub fn new(ctx: &mut EventCtx, app: &App, start: BuildingID, options: Options) -> Isochrone {
-        let time_to_reach_building = options.clone().time_to_reach_building(&app.map, start);
+        let time_to_reach_building = options.clone().times_from_buildings(&app.map, vec![start]);
 
         let mut amenities_reachable = MultiMap::new();
         let mut population = 0;

map_model/src/connectivity/mod.rs

@@ -50,11 +50,12 @@ pub fn find_scc(map: &Map, constraints: PathConstraints) -> (HashSet<LaneID>, Ha
     (largest_group, disconnected)
 }
 
-/// Starting from one building, calculate the cost to all others. If a destination isn't reachable,
-/// it won't be included in the results. Ignore results greater than the time_limit away.
+/// Starting from some initial buildings, calculate the cost to all others. If a destination isn't
+/// reachable, it won't be included in the results. Ignore results greater than the time_limit
+/// away.
 pub fn all_vehicle_costs_from(
     map: &Map,
-    start: BuildingID,
+    starts: Vec<BuildingID>,
     time_limit: Duration,
     constraints: PathConstraints,
 ) -> HashMap<BuildingID, Duration> {
@@ -77,7 +78,8 @@ pub fn all_vehicle_costs_from(
         }
     }
 
-    if let Some(start_road) = bldg_to_road.get(&start) {
+    // TODO Use all starting points
+    if let Some(start_road) = bldg_to_road.get(&starts[0]) {
         let graph = build_graph_for_vehicles(map, constraints);
         let cost_per_road = petgraph::algo::dijkstra(&graph, *start_road, None, |(_, _, mvmnt)| {
             vehicle_cost(mvmnt.from, *mvmnt, constraints, map.routing_params(), map)

map_model/src/connectivity/walking.rs

@@ -56,27 +56,34 @@ impl Ord for Item {
     }
 }
 
-/// Starting from one building, calculate the cost to all others. If a destination isn't reachable,
-/// it won't be included in the results. Ignore results greater than the time_limit away.
+/// Starting from some initial buildings, calculate the cost to all others. If a destination isn't
+/// reachable, it won't be included in the results. Ignore results greater than the time_limit
+/// away.
 ///
-/// If the start building is on the shoulder of a road and `!opts.allow_shoulders`, then the
-/// results will always be empty.
+/// If all of the start buildings are on the shoulder of a road and `!opts.allow_shoulders`, then
+/// the results will always be empty.
 pub fn all_walking_costs_from(
     map: &Map,
-    start: BuildingID,
+    starts: Vec<BuildingID>,
     time_limit: Duration,
     opts: WalkingOptions,
 ) -> HashMap<BuildingID, Duration> {
-    let start_lane = map.get_l(map.get_b(start).sidewalk_pos.lane());
-    if start_lane.lane_type == LaneType::Shoulder && !opts.allow_shoulders {
+    if !opts.allow_shoulders {
+        if starts
+            .iter()
+            .all(|b| map.get_l(map.get_b(*b).sidewalk()).lane_type == LaneType::Shoulder)
+        {
             return HashMap::new();
         }
+    }
 
     let mut queue: BinaryHeap<Item> = BinaryHeap::new();
+    for b in starts {
         queue.push(Item {
             cost: Duration::ZERO,
-        node: WalkingNode::closest(map.get_b(start).sidewalk_pos, map),
+            node: WalkingNode::closest(map.get_b(b).sidewalk_pos, map),
         });
+    }
 
     let mut cost_per_node: HashMap<WalkingNode, Duration> = HashMap::new();
     while let Some(current) = queue.pop() {