library(ggmap)
# this also loads ggplot2
# ggmap and ggplot2 installed in the virtual desktop
# internet required since we are downloading data to construct maps.

# This file contains material from the edX.org course Programming with R for Data Science
# and https://cran.r-project.org/web/packages/ggmap/ggmap.pdf

# The ggmap package:  Interfacing ggplot2 and RGoogleMaps.
# Two steps in making a mapp with ggmap:
# 1. download raster dta for the map;
# 2. create the map with ggmap(), then add layers.

# To download raster data, need to specify 
# 1. location of center
# 2. the zoom factor

# Two ways to specify location for map download.
# location or address
mylocation="Eastern Illinois University"

# or by latitude and longitude
# geocodes finds latitude and longitude 
geocode("Eastern Illinois University")
# Information from URL: 
# http://maps.googleapis.com/maps/api/geocode/json?address=Eastern%20Illinois%20University&sensor=false
#        lon      lat
# 1 -88.17591 39.47803
mylocation=c(lon=-88.17591, lat=39.47803)
# both methods will give the same results when specifying the center for the map to download

# zoom factor: 3=continent, 10=city, 21=building
mymap=get_map(location=mylocation,color="color", source="google", maptype="satellite", zoom=16)
ggmap(mymap, extent="panel", ylab="Latitude", xlab="Longitude")

# Example Pg 6
# types of input
geocode("houston texas")
geocode("baylor university") # see known issues below
geocode("1600 pennsylvania avenue, washington dc")
geocode("the white house")
geocode(c("baylor university", "salvation army waco"))

# types of output
geocode("houston texas", output = "latlona")
geocode("houston texas", output = "more")
geocode("Baylor University", output = "more")
str(geocode("Baylor University", output = "all"))

# see how many requests we have left with google
geocodeQueryCheck()
geocode("one bear place, waco, texas")
geocode("houston texas", force = TRUE)

# Example Pg 8
# geom_leg : single line segments with rounded ends

map <- get_map(
  location = c(-77.0425, 38.8925), # painfully picked by hand
  source = "google", zoom = 14, maptype = "satellite"
)
ggmap(map)
(legs_df <- route(
  "the white house, dc",
  "lincoln memorial washington dc",
  alternatives = TRUE
))
ggplot(data = legs_df) +
  geom_leg(aes(
    x = startLon, xend = endLon,
    y = startLat, yend = endLat
  )) +
  coord_map()
ggplot(data = legs_df) +
  geom_leg(aes(
    x = startLon, xend = endLon,
    y = startLat, yend = endLat,
    color = route
  )) +
  coord_map()
ggmap(map) +
  geom_leg(
    aes(
      x = startLon, xend = endLon,
      y = startLat, yend = endLat
    ),
    data = legs_df, color = "red"
  )


# Example pg 3
# bb2bbox : convert a bb specification to a bbox specification
# data frame bounding box specification

gc <- geocode("white house, washington dc")
map <- get_map(gc)
# type in the url in a web browser
(bb <- attr(map, "bb"))
(bbox <- bb2bbox(bb))
stamMap <- get_stamenmap(bbox)
# Error, map from url should be:
# http://tile.stamen.com/terrain/10/291/390.png

ggmap(map)
ggmap(map)+geom_point(aes(lon,lat),data=gc,colour="red",size=3)

ggmap(stamMap)+geom_point(aes(x=lon, y=lat),data=gc, colour = "red", size=3)
)
# Error in ggmap(stamMap) : object 'stamMap' not found

# Example Pg 4
# Wind data from Hurricane Ike
# wind dataframe from ggmap

# from data
calc_zoom(lon, lat, wind)

# from range
lon_range <- extendrange( wind$lon )
lat_range <- extendrange( wind$lat )
calc_zoom(lon_range, lat_range)

# from bounding box
box <- make_bbox(lon, lat, data = crime)
calc_zoom(box)

# Example Pg 16
map <- get_map()
map
str(map)
ggmap(map)
## Not run:
# not run by check to reduce time; also,
# osm may error due to server overload
(map <- get_map(maptype = "roadmap"))
(map <- get_map(source = "osm"))
# ERROR
(map <- get_map(source = "stamen", maptype = "watercolor"))
map <- get_map(location = "texas", zoom = 6, source = "stamen")
ggmap(map, fullpage = TRUE)

# Lightly cleaned Houston crime from January 2010 to August 2010 geocoded with Google Maps
# http://www.houstontx.gov/police/cs/stats2.htm
head(crime)

# Example Pg 14
# markers and paths are easy to access
d <- function(x=-95.36, y=29.76, n,r,a){
  round(data.frame(
    lon = jitter(rep(x,n), amount = a),
    lat = jitter(rep(y,n), amount = a)
  ), digits = r)
}
df <- d(n=50,r=3,a=.3)
map <- get_googlemap(markers = df, path = df,, scale = 2)
ggmap(map)
ggmap(map, extent = "device") +
  geom_point(aes(x = lon, y = lat), data = df, size = 3, colour = "black") +
  geom_path(aes(x = lon, y = lat), data = df)
gc <- geocode("waco, texas", source = "google")
center <- as.numeric(gc)
ggmap(get_googlemap(center = center, color = "bw", scale = 2), extent = "device")
# the scale argument can be seen in the following
# (make your graphics device as large as possible)
ggmap(get_googlemap(center, scale = 1), extent = "panel") # pixelated
ggmap(get_googlemap(center, scale = 2), extent = "panel") # fine
# archiving; note that you must meet google's terms for this condition
map <- get_googlemap(archiving = TRUE)

# default is Houston
map <- get_googlemap()
ggmap(map)


# Example Pg 20
# Stitches map tiles to get a map image from Stamen Maps.

gc <- geocode("baylor university")
google <- get_googlemap("baylor university", zoom = 15)
ggmap(google) +
  geom_point(aes(x = lon, y = lat), data = gc, colour = "red", size = 2)

bbox <- c(left = -97.132, bottom = 31.536, right = -97.105, top = 31.560)
ggmap(get_stamenmap(bbox, zoom = 13))
ggmap(get_stamenmap(bbox, zoom = 14))
ggmap(get_stamenmap(bbox, zoom = 15))
# ERROR see links; png instead of jpg
# See examples pg 21
ggmap(get_stamenmap(bbox, maptype = "terrain", zoom = 14))
# ERROR
ggmap(get_stamenmap(bbox, maptype = "toner", zoom = 14))
# NO ERROR