Mapping different states with geom_sf using facet wrap and scales free

问题

First, I am aware of this answer : Mapping different states in R using facet wrap
But I work with object of library sf.
It seems that facet_wrap(scales = "free") is not available for objects plotted with geom_sf in ggplot2. I get this message:

Erreur : Free scales are only supported with coord_cartesian() and coord_flip()

Is there any option I have missed ?
Anyone has solve the problem without being forced to use cowplot (or any other gridarrange)?

Indeed, here is an example. I would like to show the different French regions separately in facets but with their own x/y limits.

The result without scales = "free"

Scales are calculated with the extent of the entire map.

FRA <- raster::getData(name = "GADM", country = "FRA", level = 1)
FRA_sf <- st_as_sf(FRA)

g <- ggplot(FRA_sf) +
  geom_sf() +
  facet_wrap(~NAME_1)

The result using cowplot

I need to use a list of ggplots and can then combine them. This is the targeted output. It is cleaner. But I also want a clean way to add a legend. (I know may have a common legend like in this other SO question : facet wrap distorts state maps in R)

g <- purrr::map(FRA_sf$NAME_1,
           function(x) {
             ggplot() +
               geom_sf(data = filter(FRA_sf, NAME_1 == x)) +
               guides(fill = FALSE) +
               ggtitle(x)
           })

g2 <- cowplot::plot_grid(plotlist = g)

回答1:

I know you are looking for a solution using ggplot2, but I found the tmap package could be a choice depends on your need. The syntax of tmap is similar to ggplot2, it can also take sf object. Take your FRA_sf as an example, we can do something like this.

library(tmap)

tm_shape(FRA_sf) +
  tm_borders() +
  tm_facets(by = "NAME_1")

Or we can use geom_spatial from the ggspatial package, but geom_spatial only takes Spatial* object.

library(ggplot2)
library(ggspatial)

ggplot() +
  geom_spatial(FRA) + # FRA is a SpatialPolygonsDataFrame object
  facet_wrap(~NAME_1, scales = "free")

来源：https://stackoverflow.com/questions/47678480/mapping-different-states-with-geom-sf-using-facet-wrap-and-scales-free

标签

ggplot2