Dijkstra (#137)

* wip

* remove prints

* single test case, diagram comment

include/nigiri/routing/search.h

@@ -95,13 +95,6 @@ struct search {
       dijkstra(tt_, q_,
                kFwd ? tt_.fwd_search_lb_graph_ : tt_.bwd_search_lb_graph_,
                state_.travel_time_lower_bound_);
-      for (auto i = 0U; i != tt_.n_locations(); ++i) {
-        auto const lb = state_.travel_time_lower_bound_[i];
-        for (auto const c : tt_.locations_.children_[location_idx_t{i}]) {
-          state_.travel_time_lower_bound_[to_idx(c)] =
-              std::min(lb, state_.travel_time_lower_bound_[to_idx(c)]);
-        }
-      }
       UTL_STOP_TIMING(lb);
       stats_.lb_time_ = static_cast<std::uint64_t>(UTL_TIMING_MS(lb));
 

src/routing/dijkstra.cc

@@ -53,14 +53,21 @@ void dijkstra(timetable const& tt,
   auto pq = dial<label, get_bucket>{kMaxTravelTime.count()};
   for (auto const& [l, duration] : min) {
     auto const d = duration;
-    for_each_meta(tt, q.start_match_mode_, l, [&](location_idx_t const meta) {
+    for_each_meta(tt, q.dest_match_mode_, l, [&](location_idx_t const meta) {
       pq.push(label{meta, d});
       dists[to_idx(meta)] = std::min(d, dists[to_idx(meta)]);
       trace("DIJKSTRA INIT @{}: {}\n", location{tt, meta}, duration);
     });
   }
 
   dijkstra(lb_graph, pq, dists);
+
+  for (auto i = 0U; i != tt.n_locations(); ++i) {
+    auto const lb = dists[i];
+    for (auto const c : tt.locations_.children_[location_idx_t{i}]) {
+      dists[to_idx(c)] = std::min(lb, dists[to_idx(c)]);
+    }
+  }
 }
 
 }  // namespace nigiri::routing

test/routing/dijkstra_test.cc

@@ -0,0 +1,133 @@
+#include "gtest/gtest.h"
+
+#include "nigiri/loader/gtfs/files.h"
+#include "nigiri/loader/gtfs/load_timetable.h"
+#include "nigiri/loader/init_finish.h"
+#include "nigiri/routing/dijkstra.h"
+#include "nigiri/routing/query.h"
+#include "nigiri/timetable.h"
+
+using namespace date;
+using namespace nigiri;
+using namespace nigiri::loader;
+using namespace nigiri::routing;
+
+namespace {
+
+/*
+            10 min walk
+            ┌────────────────┐
+            │                │
+            │     ┌──────────┼──┐
+            │     │      │      │10:30
+            │     │      │  D2  ┼─────────────────┐
+            │     │      │      │                 │
+            │     │──────┼──────│                 │
+            │     │      │      │                 │
+            └─────┼  D1  │      │D                │
+                  │      │      │            11:30│
+                  └─┬───────────┘      ┌──────────▼──┐
+                    │09:30             │      │      │
+                    │                 C│      │  C2  ┼──┐
+                    │                  │      │      │  │
+                    │                  │──────┼──────│  │
+                    │09:45             │      │      │  │
+┌───┐09:00        ┌─▼─┐                │  C1  │      │  │
+│ A ├────────────►│ B ┼────────────────►      │      │  │
+└───┘       09:30 └───┘10:00      11:00└───┬─────────┘  │
+                                           │            │
+                                           └────────────┘
+                                               15 min walk
+ */
+mem_dir dijkstra_files() {
+  return mem_dir::read(R"__(
+"(
+# agency.txt
+agency_id,agency_name,agency_url,agency_timezone
+MTA,MOTIS Transit Authority,https://motis-project.de/,Europe/Berlin
+
+# calendar_dates.txt
+service_id,date,exception_type
+S,20240608,1
+
+# stops.txt
+stop_id,stop_name,stop_desc,stop_lat,stop_lon,stop_url,location_type,parent_station
+A,A,A,,,,0,
+B,B,B,,,,0,
+C,C,C,,,,0,
+C1,C1,C1,,,,0,C
+C2,C2,C2,,,,0,C
+D,D,D,,,,1,
+D1,D1,D1,,,,0,D
+D2,D2,D2,,,,0,D
+
+# routes.txt
+route_id,agency_id,route_short_name,route_long_name,route_desc,route_type
+AB,MTA,AB,AB,A -> B,0
+BC,MTA,BC,BC,B -> C,0
+DB,MTA,DB,DB,D -> B,0
+DC,MTA,DC,DC,D -> C,0
+
+# trips.txt
+route_id,service_id,trip_id,trip_headsign,block_id
+AB,S,AB_TRP,AB_TRP,1
+BC,S,BC_TRP,BC_TRP,2
+DB,S,DB_TRP,DB_TRP,3
+DC,S,DC_TRP,DC_TRP,4
+
+# stop_times.txt
+trip_id,arrival_time,departure_time,stop_id,stop_sequence,pickup_type,drop_off_type
+AB_TRP,09:00,09:00,A,0,0,0
+AB_TRP,09:30,09:30,B,1,0,0
+DB_TRP,09:30,09:30,D1,0,0,0
+DB_TRP,09:45,09:45,B,1,0,0
+BC_TRP,10:00,10:00,B,0,0,0
+BC_TRP,11:00,11:00,C2,1,0,0
+DC_TRP,10:30,10:30,D2,0,0,0
+DC_TRP,11:30,11:30,C1,1,0,0
+
+# transfers.txt
+from_stop_id,to_stop_id,transfer_type,min_transfer_time
+D1,D2,2,600
+D2,D1,2,600
+C1,C2,2,900
+C2,C1,2,900
+
+)__");
+}
+}  // namespace
+
+TEST(routing, dijkstra) {
+  timetable tt;
+  tt.date_range_ = {sys_days{2024_y / June / 7}, sys_days{2024_y / June / 9}};
+  register_special_stations(tt);
+  auto const src = source_idx_t{0U};
+  gtfs::load_timetable({}, src, dijkstra_files(), tt);
+  finalize(tt);
+
+  auto const d1_l = tt.locations_.location_id_to_idx_.at({"D1", src});
+  auto const q_d1_c2 = query{
+      .start_time_ = unixtime_t{sys_days{2024_y / June / 8} + 7_hours},
+      .start_match_mode_ = location_match_mode::kExact,
+      .dest_match_mode_ = location_match_mode::kExact,
+      .start_ = {{d1_l, 0_minutes, 0U}},
+      .destination_ = {{tt.locations_.location_id_to_idx_.at({"C2", src}),
+                        0_minutes, 0U}},
+  };
+  auto dists = std::vector<std::uint16_t>{};
+  dijkstra(tt, q_d1_c2, tt.fwd_search_lb_graph_, dists);
+  EXPECT_EQ(60U, dists[d1_l.v_]);
+
+  auto const d_l = tt.locations_.location_id_to_idx_.at({"D", src});
+  auto const q_d_c = query{
+      .start_time_ = unixtime_t{sys_days{2024_y / June / 8} + 7_hours},
+      .start_match_mode_ = location_match_mode::kEquivalent,
+      .dest_match_mode_ = location_match_mode::kEquivalent,
+      .start_ = {{d_l, 0_minutes, 0U}},
+      .destination_ = {{tt.locations_.location_id_to_idx_.at({"C", src}),
+                        0_minutes, 0U}},
+  };
+  dists = std::vector<std::uint16_t>{};
+  dijkstra(tt, q_d_c, tt.fwd_search_lb_graph_, dists);
+  EXPECT_EQ(60U, dists[d_l.v_]);
+}