ggmap (version 2.1)

get_googlemap: Get a Google Map

Description

get_googlemap accesses the Google Static Maps API version 2 to download a static map.

Usage

get_googlemap(center = c(lon = -95.3632715, lat = 29.7632836),
    zoom = 10, size = c(640, 640), scale = 2,
    format = c("png8", "gif", "jpg", "jpg-baseline", "png32"),
    maptype = c("terrain", "satellite", "roadmap", "hybrid"),
    language = "en-EN", region, markers, path, visible,
    style, sensor = FALSE, messaging = FALSE,
    urlonly = FALSE, filename = "ggmapTemp",
    color = c("color", "bw"), ...)

Arguments

center

the center of the map. this can either be 1. a longitude/latitude numeric vector or 2. a character string address (note that the latter uses a geocode)

zoom

map zoom, an integer from 0 (whole world) to 21 (building), default value 10 (city)

size

rectangular dimensions of map in pixels - horizontal x vertical - with a max of c(640, 640). this parameter is affected in a multiplicative way by scale.

scale

multiplicative factor for the number of pixels returned possible values are 1, 2, or 4 (e.g. size = c(640,640) and scale = 2 returns an image with 1280x1280 pixels). 4 is reserved for google business users only. scale also affects the size of la

format

character string providing image format - png, jpeg, and gif formats available in various flavors

maptype

character string providing google map theme. options available are 'terrain', 'satellite', 'roadmap', and 'hybrid'

language

character string providing language of map labels (for themes with them) in the format 'en-EN'. not all languages are supported; for those which aren't the default language is used

region

borders to display as a region code specified as a two-character ccTLD ('top-level domain') value, see http://en.wikipedia.org/wiki/List_of_Internet_top-level_domains#Country_code_top-level_domains

markers

data.frame with first column longitude, second column latitude, for which google markers should be embedded in the map image, or character string to be passed directly to api

path

data.frame (or list of data.frames) with first column longitude, second column latitude, for which a single path should be embedded in the map image, or character string to be passed directly to api

visible

a location as a longitude/latitude numeric vector (or data frame with first column longitude, second latitude) or vector of character string addresses which should be visible in map extent

style

character string to be supplied directly to the api for the style argument . this is a powerful complex specification, see https://developers.google.com/maps/documentation/staticmaps/

sensor

specifies whether the application requesting the static map is using a sensor to determine the user's location

messaging

turn messaging on/off

urlonly

return url only

filename

destination file for download (file extension added according to format)

color

color or black-and-white

...

...

Value

• a map image as a 2d-array of colors as hexadecimal strings representing pixel fill values.

See Also

https://developers.google.com/maps/documentation/staticmaps/, ggmap

Examples

get_googlemap(urlonly = TRUE)

# get_googlemap has several argument checks
get_googlemap(zoom = 13.5)
get_googlemap(scale = 3)
get_googlemap(center = c(-30,-110))

# 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, fullpage = TRUE) +
  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')
center <- as.numeric(gc)
ggmap(get_googlemap(center = center, color = 'bw', scale = 2), fullpage = T)

# the scale argument can be seen in the following
# (make your graphics device as large as possible)
ggmap(get_googlemap(center, scale = 1), fullpage = TRUE) # pixelated
ggmap(get_googlemap(center, scale = 2), fullpage = TRUE) # fine