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Estimate drive times/distances for specific origin-destination pairs

osrm_table_pairs.Rd

A wrapper around osrm::osrmTable() for when only specific origin-destination pairs are needed, rather than the full matrix of travel times/distances between every combination of points. Rather than sending every unique origin and every unique destination to a single osrm::osrmTable() call (which would request the full cross-product between them), pairs are grouped by whichever of origins or destinations has fewer unique points, and one osrm::osrmTable() call is made per group, scoped only to the counterpart points actually paired with it. This keeps each request small and avoids hitting a server's max-table-size limit when there are many distinct pairs, at the cost of issuing more requests than a single full-matrix call.

Usage

osrm_table_pairs(
  origins,
  destinations,
  exclude,
  measure = "duration",
  osrm.server = getOption("osrm.server", "https://routing.openstreetmap.de/"),
  osrm.profile = getOption("osrm.profile", "car")
)

Arguments

origins

Origin points, one row per pair, as an sf or sfc object of type POINT. If relevant, row names are used as identifiers.

destinations

Destination points, one row per pair, matching origins row for row, as an sf or sfc object of type POINT with the same CRS as origins.

exclude

Passed to osrm::osrmTable(): an optional "exclude" request option for the OSRM API (not allowed with the OSRM demo server).

measure

A character indicating what measures are calculated. It can be "duration" (in minutes), "distance" (in meters), or both c("duration", "distance").

osrm.server

The base URL of the routing server.

osrm.profile

The routing profile to use, e.g. "car", "bike" or "foot".

Value

A tibble with one row per origin-destination pair, including the origin and destination coordinates and ids, and the requested duration (in minutes) and/or distance (in meters) columns. If a request for a group of pairs fails twice (the original attempt plus one retry), those pairs are returned with NA duration/distance rather than aborting the whole call, and a warning reports how many pairs failed.

Examples

if (FALSE) { # \dontrun{
origins <- sf::st_as_sf(
  data.frame(lon = c(13.38, 13.40), lat = c(52.52, 52.50)),
  coords = c("lon", "lat"), crs = 4326
)
destinations <- sf::st_as_sf(
  data.frame(lon = c(13.41, 13.39), lat = c(52.53, 52.51)),
  coords = c("lon", "lat"), crs = 4326
)
osrm_table_pairs(origins, destinations)
} # }