Plotting location Data (by longitude/latitude and station)

new_locations <- subset(locations, lon != "unknown") #one station has no location, removed from data set
station_ids2 <- row.names(new_locations)

#maptype options are “terrain”, “satellite”, “roadmap”, and “hybrid”
map2 <- get_map(location = c(-120.5, 35.4), zoom = 9, maptype = "terrain", scale = 2)
## Map from URL : http://maps.googleapis.com/maps/api/staticmap?center=35.4,-120.5&zoom=9&size=640x640&scale=2&maptype=terrain&language=en-EN&sensor=false
ggmap(map2) + geom_point(data = new_locations, 
      aes(x = as.numeric(lon), y = as.numeric(lat), fill = "red"), 
      size = 3, shape = 21) + guides(fill=FALSE, alpha=FALSE, size=FALSE)  + 
      labs(title =  "San Luis Obispo County Station Locations", 
      x = "Longitude", y = "Latitude")