Graph #179 explains how to show a map with the leaflet R library. To specify which area of the map you want to show, just specify latitude, longitude and how much you want to zoom.

#Library
library(leaflet)

# We always initiate a leaflet map with the leaflet() function
m=leaflet()
# Then we Add default OpenStreetMap map tiles
m=addTiles(m)
# We can choose a zone:
m=setView(m, lng = 166.45, lat = -21, zoom = 7)
m

# Same stuff but using the %>% operator
m=leaflet() %>% addTiles() %>% setView( lng = 166.45, lat = -22.25, zoom = 8 )
m