Shortest route(s) between two nodes, with geometry

The sf routing interface, uniform with the rest of the ox_route_* family: computes the minimum-weight route from from to to (Dijkstra, in the Rust core) and returns it with its cost and merged street geometry. With k > 1 it returns up to k loopless route alternatives (Yen's algorithm), one per row, ordered by increasing cost.

Usage

ox_route_shortest(g, from, to, weight = "length", k = 1)

Arguments

g: An osm_graph.
from, to: Node osmids (as returned by ox_nearest_nodes()).
weight: Edge column used as weight. Default "length"; use "travel_time" after ox_add_edge_travel_times() for fastest routes.
k: Number of route alternatives to return. Default 1 (the shortest route); larger values enumerate loopless alternatives by increasing cost (fewer than k rows are returned when fewer distinct routes exist).

Value

An sf tibble with one row per route: route (rank), cost, a list-column path of the node osmids traversed, and the route's merged street geometry. An error is raised when to is unreachable from from.

Details

The geometry is built from the edges the solver actually traversed, so it is exact across parallel edges. ox_shortest_path() and ox_k_shortest_paths() remain as the lighter variants returning only node sequences.

Examples

g <- example_osm_graph()
from <- ox_nearest_nodes(g, 0, 0)
to <- ox_nearest_nodes(g, 300, 300)
ox_route_shortest(g, from, to)
#> Simple feature collection with 1 feature and 3 fields
#> Geometry type: LINESTRING
#> Dimension:     XY
#> Bounding box:  xmin: 0 ymin: 0 xmax: 300 ymax: 300
#> Projected CRS: WGS 84 / Pseudo-Mercator
#> # A tibble: 1 × 4
#>   route  cost path                                                   geometry
#>   <int> <dbl> <list>                                         <LINESTRING [m]>
#> 1     1   600 <int [7]> (0 0, 100 0, 200 0, 300 0, 300 100, 300 200, 300 300)
ox_route_shortest(g, from, to, k = 3)
#> Simple feature collection with 3 features and 3 fields
#> Geometry type: LINESTRING
#> Dimension:     XY
#> Bounding box:  xmin: 0 ymin: 0 xmax: 300 ymax: 300
#> Projected CRS: WGS 84 / Pseudo-Mercator
#> # A tibble: 3 × 4
#>   route  cost path                                                      geometry
#>   <int> <dbl> <list>                                            <LINESTRING [m]>
#> 1     1   600 <int [7]>    (0 0, 100 0, 200 0, 300 0, 300 100, 300 200, 300 300)
#> 2     2   600 <int [7]> (0 0, 0 100, 100 100, 100 200, 100 300, 200 300, 300 30…
#> 3     3   600 <int [7]> (0 0, 100 0, 100 100, 100 200, 100 300, 200 300, 300 30…