mp_map function

Get static map from the Maps Static API

Download a static map from the Maps Static API, given map center and zoom level.

mp_map(
  center,
  zoom = 10L,
  maptype = c("roadmap", "satellite", "terrain", "hybrid"),
  size = c(640L, 640L),
  scale = 2L,
  style = NULL,
  key,
  quiet = FALSE
)

Arguments

• center: Character of length 1 of the form "lat,lon" or a geometry of class sfg, sfc or sf. If center is a geometry, the center of the geometry bounding box is passed as map center. Missing Coordinate Reference System (CRS) is assumed WGS84.
• zoom: Zoom level, a positive integer or zero. The appropriate range is 0 to 21. Defaults to 10.
• maptype: Map type, one of: "roadmap", "satellite", "terrain", "hybrid".
• size: Numeric of length 2, the width and height of the map in pixels. The default is the maximum size allowed (640x640). The final dimensions of the image are affected by scale.
• scale: Integer, factor to multiply size and determine the final image size. Allowed values are 1 and 2, defaults to 2.
• style: List of named character vector(s) specifying style directives. The full style reference is available at https://developers.google.com/maps/documentation/maps-static/style-reference, see examples below.
• key: Google APIs key
• quiet: Logical; suppress printing URL for Google Maps API call (e.g. to hide API key)

Returns

A stars raster with the requested map, in Web Mercator CRS (EPSG:3857).

Examples

## Not run:

library(stars)
key = readLines("~/key")

# Using coordinates
r = mp_map("31.253205,34.791914", 14, key = key)
plot(r)

# Using 'sfc' point - WGS84
pnt = st_point(c(34.791914, 31.253205))
pnt = st_sfc(pnt, crs = 4326)
r = mp_map(pnt, 14, key = key)
plot(r)

# Using 'sfc' point - UTM
pnt = st_point(c(34.791914, 31.253205))
pnt = st_sfc(pnt, crs = 4326)
pnt = st_transform(pnt, 32636)
r = mp_map(pnt, 14, key = key)
plot(r)

# Using 'sfc' polygon
pnt = st_point(c(34.791914, 31.253205))
pnt = st_sfc(pnt, crs = 4326)
pol = st_buffer(pnt, 0.01)
r = mp_map(pol, 14, key = key)
plot(r)

# 'ggplot2'
library(ggplot2)
cols = attr(r[[1]], "colors")
ggplot() +
  geom_stars(data = r, aes(x = x, y = y, fill = color)) +
  scale_fill_manual(values = cols, guide = FALSE) +
  coord_sf()

# 'ggplot2' - map types
r1 = mp_map(pnt, 14, maptype = "roadmap", key = key)
r2 = mp_map(pnt, 14, maptype = "satellite", key = key)
r3 = mp_map(pnt, 14, maptype = "terrain", key = key)
r4 = mp_map(pnt, 14, maptype = "hybrid", key = key)
cols1 = attr(r1[[1]], "colors")
cols2 = attr(r2[[1]], "colors")
cols3 = attr(r3[[1]], "colors")
cols4 = attr(r4[[1]], "colors")
theme1 = theme(
  axis.text = element_blank(),
  axis.title = element_blank(),
  axis.ticks = element_blank()
)
g1 = ggplot() +
  geom_stars(data = r1, aes(x = x, y = y, fill = color)) +
  scale_fill_manual(values = cols1, guide = FALSE) +
  coord_sf() +
  ggtitle("roadmap") +
  theme1
g2 = ggplot() +
  geom_stars(data = r2, aes(x = x, y = y, fill = color)) +
  scale_fill_manual(values = cols2, guide = FALSE) +
  coord_sf() +
  ggtitle("satellite") +
  theme1
g3 = ggplot() +
  geom_stars(data = r3, aes(x = x, y = y, fill = color)) +
  scale_fill_manual(values = cols3, guide = FALSE) +
  coord_sf() +
  ggtitle("terrain") +
  theme1
g4 = ggplot() +
  geom_stars(data = r4, aes(x = x, y = y, fill = color)) +
  scale_fill_manual(values = cols4, guide = FALSE) +
  coord_sf() +
  ggtitle("hybrid") +
  theme1
g1 + g2 + g3 + g4

# styled maps
nl = list(
  c(feature = 'all', element = 'labels', visibility = 'off')
)
nb = list(
  c(feature = 'poi.business', visibility = 'off'),
  c(feature = 'poi.medical', visibility = 'off')
)
r_nl = mp_map(pnt, 14, key = key, style = nl)
plot(r_nl)
r_nb = mp_map(pnt, 14, key = key, style = nb)
plot(r_nb)
## End(Not run)

References

https://developers.google.com/maps/documentation/maps-static/overview