get_grayscale_map: Get a grayscaled Google Map.
In walshc/grayscaleMap: Grayscale version of ggmap

Description Usage Arguments Value Author(s) See Also Examples

get_grayscale_map accesses the Google Static Maps API version 2 to download a static map. Note that in most cases by using this function you are agreeing to the Google Maps API Terms of Service at https://developers.google.com/maps/terms.

get_grayscale_map(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", messaging = FALSE, urlonly = FALSE,
  filename = "ggmapTemp", color = c("color", "bw"), force = FALSE,
  where = tempdir(), archiving = FALSE, ext = "com", inject = "",
  region, markers, path, visible, style, ...)

`center`	the center of the map. Either a longitude/latitude numeric vector, a string address (note that the latter uses `geocode` with `source = "google"`).
`zoom`	map zoom, an integer from 3 (continent) 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 labels as well.
`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
`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
`force`	if the map is on file, should a new map be looked up?
`where`	where should the file drawer be located (without terminating "/")
`archiving`	use archived maps. note: by changing to TRUE you agree to the one of the approved uses listed in the Google Maps API Terms of Service : http://developers.google.com/maps/terms.
`ext`	domain extension (e.g. "com", "co.nz")
`inject`	character string to add to the url
`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 or a named vector (see examples). this is a powerful complex specification, see https://developers.google.com/maps/documentation/staticmaps/
`...`	...

a ggmap object (a classed raster object with a bounding box attribute)

David Kahle david.kahle@gmail.com

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

## Not run:  # to diminish run check time


get_grayscale_map(urlonly = TRUE)
ggmap::ggmap(get_grayscale_map())


# 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_grayscale_map(markers = df, path = df, scale = 2)
ggmap::ggmap(map)
ggmap::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 <- ggmap::geocode("waco, texas", source = "google")
center <- as.numeric(gc)
ggmap::ggmap(get_grayscale_map(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::ggmap(get_grayscale_map(center, scale = 1), extent = "panel") # pixelated
ggmap::ggmap(get_grayscale_map(center, scale = 2), extent = "panel") # fine

# archiving; note that you must meet google's terms for this condition
map <- get_grayscale_map(archiving = TRUE)
map <- get_grayscale_map()
ggmap::ggmap(map)


# style
map <- get_grayscale_map(
  maptype = "roadmap",
  style = c(feature = "all", element = "labels", visibility = "off"),
  color = "bw"
)
ggmap::ggmap(map)





## End(Not run)