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Asked: 2026-05-27T09:56:40+00:00

In R, using maps package, and gcIntermediate function, how do I draw lines between

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In R, using maps package, and gcIntermediate function, how do I draw lines between two countries? It needs lat-long, but I’m not sure what lat-long should I give for countries (say I want to draw a line between USA and sweden)

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  1. Editorial Team

    There are multiple maps you could use, depending on what info/detail/etc. you need, but for this the very nice wrld_simpl will do just fine:

    library(maptools)
library(geosphere)

data(wrld_simpl)

US_lat = wrld_simpl$LAT[wrld_simpl$NAME == 'United States']
US_lon = wrld_simpl$LON[wrld_simpl$NAME == 'United States']

SWE_lat = wrld_simpl$LAT[wrld_simpl$NAME == 'Sweden']
SWE_lon = wrld_simpl$LON[wrld_simpl$NAME == 'Sweden']

points = gcIntermediate(c(US_lon, US_lat), c(SWE_lon, SWE_lat), 100)

dev.new(width=6, height=4)
plot(wrld_simpl)
lines(points, col='red')

    enter image description here

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