pgrouting: Geospatial Routing

pgRouting is PostgreSQL and PostGIS extension adding geospatial routing functionality.

The core functionality of pgRouting is a set of path finding algorithms including:

• All Pairs Shortest Path, Johnson’s Algorithm
• All Pairs Shortest Path, Floyd-Warshall Algorithm
• Shortest Path A*
• Bi-directional Dijkstra Shortest Path
• Bi-directional A* Shortest Path
• Shortest Path Dijkstra
• Driving Distance
• K-Shortest Path, Multiple Alternative Paths
• K-Dijkstra, One to Many Shortest Path
• Traveling Sales Person
• Turn Restriction Shortest Path (TRSP)

Enable the extension#

Example#

As an example, we'll solve the traveling salesman probelem using the pgRouting's pgr_TSPeuclidean function from some PostGIS coodinates.

A summary of the traveling salesman problem is, given a set of city coordinates, solve for a path that goes through each city and minimizes the total distance traveled.

First we populate a table with some X, Y coordinates

create table wi29 (
  id bigint,
  x float,
  y float,
  geom geometry
);

insert into wi29 (id, x, y)
values
  (1,20833.3333,17100.0000),
  (2,20900.0000,17066.6667),
  (3,21300.0000,13016.6667),
  (4,21600.0000,14150.0000),
  (5,21600.0000,14966.6667),
  (6,21600.0000,16500.0000),
  (7,22183.3333,13133.3333),
  (8,22583.3333,14300.0000),
  (9,22683.3333,12716.6667),
  (10,23616.6667,15866.6667),
  (11,23700.0000,15933.3333),
  (12,23883.3333,14533.3333),
  (13,24166.6667,13250.0000),
  (14,25149.1667,12365.8333),
  (15,26133.3333,14500.0000),
  (16,26150.0000,10550.0000),
  (17,26283.3333,12766.6667),
  (18,26433.3333,13433.3333),
  (19,26550.0000,13850.0000),
  (20,26733.3333,11683.3333),
  (21,27026.1111,13051.9444),
  (22,27096.1111,13415.8333),
  (23,27153.6111,13203.3333),
  (24,27166.6667,9833.3333),
  (25,27233.3333,10450.0000),
  (26,27233.3333,11783.3333),
  (27,27266.6667,10383.3333),
  (28,27433.3333,12400.0000),
  (29,27462.5000,12992.2222);

Next we use the pgr_TSPeuclidean function to find the best path.

select
    *
from
     pgr_TSPeuclidean($$select * from wi29$$)

 seq | node |       cost       |     agg_cost     
-----+------+------------------+------------------
   1 |    1 |                0 |                0
   2 |    2 |  74.535614157127 |  74.535614157127
   3 |    6 | 900.617093380362 | 975.152707537489
   4 |   10 | 2113.77757765045 | 3088.93028518793
   5 |   11 | 106.718669615254 | 3195.64895480319
   6 |   12 | 1411.95293791574 | 4607.60189271893
   7 |   13 | 1314.23824873744 | 5921.84014145637
   8 |   14 | 1321.76283931305 | 7243.60298076942
   9 |   17 | 1202.91366735569 |  8446.5166481251
  10 |   18 | 683.333268292684 | 9129.84991641779
  11 |   15 | 1108.05137466134 | 10237.9012910791
  12 |   19 | 772.082339448903 |  11009.983630528
  13 |   22 | 697.666150054665 | 11707.6497805827
  14 |   23 | 220.141999627513 | 11927.7917802102
  15 |   21 | 197.926372783442 | 12125.7181529937
  16 |   29 | 440.456596290771 | 12566.1747492844
  17 |   28 | 592.939989005405 | 13159.1147382898
  18 |   26 | 648.288376333318 | 13807.4031146231
  19 |   20 | 509.901951359278 | 14317.3050659824
  20 |   25 | 1330.83095428717 | 15648.1360202696
  21 |   27 |  74.535658878487 | 15722.6716791481
  22 |   24 | 559.016994374947 |  16281.688673523
  23 |   16 | 1243.87392358622 | 17525.5625971092
  24 |    9 |  4088.0585364911 | 21613.6211336004
  25 |    7 |  650.85409697993 | 22264.4752305803
  26 |    3 | 891.004385199336 | 23155.4796157796
  27 |    4 | 1172.36699411442 |  24327.846609894
  28 |    8 | 994.708187806297 | 25322.5547977003
  29 |    5 | 1188.01888359478 | 26510.5736812951
  30 |    1 | 2266.91173136004 | 28777.4854126552

Resources#

• Official pgRouting documentation