bb2bbox: Convert a bb specification to a bbox specification

In fresques/ggmap: Spatial Visualization with ggplot2

Description

In ggmap, all maps (class ggmap) have the bb attribute, a data frame bounding box specification in terms of the bottom left and top right points of the spatial extent. This function converts this specification to a named double vector (with names left, bottom, right, top) specification that is used in some querying functions (e.g. get_stamenmap).

Usage

bb2bbox(bb)

Arguments

bb	a bounding box in bb format (see examples)

Value

a bounding box in bbox format (see examples)

Author(s)

David Kahle [e-mail]

Examples

## Not run: # cut down on R CMD check time

# grab a center/zoom map and compute its bounding box
gc <- geocode("white house, washington dc")
map <- get_map(gc)
(bb <- attr(map, "bb"))
(bbox <- bb2bbox(bb))

# use the bounding box to get a stamen map
stamMap <- get_stamenmap(bbox)

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

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



## End(Not run)

fresques/ggmap documentation built on May 28, 2019, 8:40 p.m.