# Transport routing with stplanr

    library(stplanr)

# Introduction

Routing is the process of identifying routes that enable movement between two geographic locations along the shortest path (based on mode-specific routing profiles) or in some other ‘optimal’ way, based on route network data. Most open routing engines rely on OpenStreetMap (OSM) data.

We will use the example of the Isle of Wight to demonstrate routing engines. To get OSM data for the Isle of Wight you can run the following commands:

    remotes::install_github("itsleeds/geofabrik")
    library(geofabrik)
    roads_iow = get_geofabrik(name = "Isle of Wight")
    f = gf_filename("Isle of Wight")
    file.copy(f, "iow.pbf")
    options(osrm.server = "https://0.0.0.0:5000/", osrm.profile = "driving")

# OSRM

Routing services such as OpenStreetMap Routing Machine (OSRM) require an input network, usually from OSM.

We will use the `osrm` package:

    library(osrm)
    #> Data: (c) OpenStreetMap contributors, ODbL 1.0 - http://www.openstreetmap.org/copyright
    #> Routing: OSRM - http://project-osrm.org/

In the system terminal run the following commands to make the OSRM docker image work for you.

    docker run -t -v "${PWD}:/data" osrm/osrm-backend osrm-extract -p /opt/car.lua /data/iow.pbf
    docker run -t -v "${PWD}:/data" osrm/osrm-backend osrm-partition /data/iow.osrm
    docker run -t -v "${PWD}:/data" osrm/osrm-backend osrm-customize /data/iow.osrm
    docker run -t -i -p 5000:5000 -v "${PWD}:/data" osrm/osrm-backend osrm-routed --algorithm mld /data/iow.osrm
    curl "https://127.0.0.1:5000/route/v1/driving/13.388860,52.517037;13.385983,52.496891?steps=true"

Now we can do routing in R!

On a single route:

    l = pct::wight_lines_30
    p = line2points(l)
    r = osrm::osrmRoute(src = p[1, ], dst = p[2, ], returnclass = "sf", overview = "full")
    plot(r)

And to find many routes via the `route()` function, resulting in something like the figure below.

    routes_osrm = route(l = l, route_fun = osrmRoute, returnclass = "sf", overview = "full")
    rnet_osrm = overline(routes_osrm, attrib = "bicycle")
    mapview::mapview(rnet_osrm, lwd = rnet_osrm$bicycle / 10)

    # tidy up
    f = list.files(pattern = "iow")
    unlink(x = f, recursive = TRUE)

Shut down the docker container.

    docker ps
    docker stop stupefied_hopper