Merge pull request #911 from seancarmody/sp_fortify_fix

Fix fortify-spatial namespace issue (#879)

Author: hadley

NEWS

@@ -12,6 +12,8 @@ ggplot2 0.9.3.1.99
 
 * `ggpcp()`, `ggfluctuation()`, `ggmissing()`, `ggstructure()`, and
   `ggorder()` are now defunct and have been removed.
+ 
+* `fortify.SpatialPolygonsDataFrame()` now calls `polygons` without requiring the `sp` to be loaded first. Addresses issue #879 https://github.com/hadley/ggplot2/issues/879
 
 * `aes()` no more treats variables like `a..x..b` as a calculated aesthetic
   (@krlmlr, #834).

R/fortify-spatial.r

@@ -27,7 +27,7 @@ fortify.SpatialPolygonsDataFrame <- function(model, data, region = NULL, ...) {
     coords <- ldply(model@polygons,fortify)
     message("Regions defined for each Polygons")
   } else {
-    cp <- polygons(model)
+    cp <- sp::polygons(model)
     try_require("maptools")
 
     # Union together all polygons that make up a region