geom_sf compatibility trick

[lepennec]

Moving the x/y aesthetic seems to make ggmap compatible with the new geom_sf.

Note that the crs of the geom_sf should be set to "+init=epsg:4326" in order to be compatible with the google map crs.

Example:

library(tidyverse)
library(sf)
library(ggmap)

data(meuse, package = "sp") # load data.frame from sp

meuse_sf = st_as_sf(meuse, coords = c("x", "y"), crs = 28992) %>%
  st_transform(crs = 4326)

meuse_bbox <- st_bbox(meuse_sf)

meuse_location <- c(lon = (meuse_bbox["xmin"]+meuse_bbox["xmax"])/2,
                 lat = (meuse_bbox["ymin"]+meuse_bbox["ymax"])/2)

meuse_map <- get_map(meuse_location, zoom = 13)

ggmap(meuse_map) + geom_sf(data = meuse_sf) +
  coord_sf(xlim = c(meuse_bbox["xmin"] - .1 * (meuse_bbox["xmax"]-meuse_bbox["xmin"]),
                    meuse_bbox["xmax"] + .1 * (meuse_bbox["xmax"]-meuse_bbox["xmin"])),
           ylim = c(meuse_bbox["ymin"] - .1 * (meuse_bbox["ymax"]-meuse_bbox["ymin"]),
                    meuse_bbox["ymax"] + .1 * (meuse_bbox["ymax"]-meuse_bbox["ymin"])))

yields

Note that I had to apply pull request #154 in order to make ggmap works with the github version of ggplot2.