Countries With the Most Neighbors

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library(sf)

library(maptools)

data(wrld_simpl)

# Set this to what you like

km <- 100

countries <- st_as_sf(wrld_simpl)

treshold <- km

units(treshold) <- 'km'

get_number_of_countries <- function(country, countries, treshold){

distance <- st_distance(country, countries)

is_within_treshold <- distance < treshold

number_of_countries <- sum(is_within_treshold)

return(number_of_countries)

}

result <- list()

for (i in 1:length(countries)){

country <- countries[i,]

result[[as.character(country$NAME)]] <- get_number_of_countries(country, countries, treshold)

}