Add other example to map section + ref

[stephaneguerrier]

Here is another example we could add to map example:

library(ggmap)
places <- c("Old main, penn state", "Beaver staduim, penn state")
places_coord <- geocode(places)
pennstate <- get_googlemap("Creamery, Penn state university", zoom = 15, maptype = 'satellite',
                           markers = places_coord)
route <- route(places[1], places[2], mode = "walking")
ggmap(pennstate) + geom_path(
  aes(x = startLon, y = startLat),  colour = "red", size = 1.5,
  data = route, lineend = "round"
)

It should like this:

Also we should add a ref to (ggmap : Spatial Visualization with
ggplot2)[http://stat405.had.co.nz/ggmap.pdf]

Here is another example I have made: