Great-circle distance between two countries

Haversine distance (km) between two countries' centroids – the lightweight companion to country_borders() for "how far apart" rather than "do they touch". Works from the bundled country_meta centroids, so unlike most of the spatial toolkit it needs neither sf nor the network.

Usage

distance_between(a, b, origin = "country.name")

Arguments

a, b

Vectors of country names or codes. Either the same length, or one of them length 1 to compare one country against many.

origin

How to read a/b (default "country.name").

Value

A numeric vector of great-circle distances in kilometres (NA for any country that doesn't resolve to a known centroid).

Countries without a bundled centroid

country_meta carries no centroid for a handful of small or dependent territories (Bouvet Island, the British Virgin Islands, Gibraltar, Hong Kong, Macao, Svalbard and Jan Mayen, Tokelau, Tuvalu, the U.S. Minor Outlying Islands and the Aland Islands), and no row at all for Kosovo, because countrycode::codelist has none. Those inputs return NA here even though the geometry backends do map them – so neighbors() and country_borders() know about Kosovo while this function does not.

Examples

distance_between("France", "Germany")
#> [1] 802.3524
distance_between("USA", c("Canada", "Mexico"))
#> [1] 2184.930 1622.586