Running examples in ‘gpclib-Ex.R’ failed
The error most likely occurred in:

> base::assign(".ptime", proc.time(), pos = "CheckExEnv")
> ### Name: gpc.poly-class
> ### Title: Class "gpc.poly"
> ### Aliases: gpc.poly-class [,gpc.poly,ANY,ANY-method [,gpc.poly-method
> ###   append.poly,gpc.poly,gpc.poly-method area.poly,gpc.poly-method
> ###   coerce,matrix,gpc.poly-method coerce,data.frame,gpc.poly-method
> ###   coerce,gpc.poly,matrix-method coerce,gpc.poly,numeric-method
> ###   coerce,numeric,gpc.poly-method coerce,list,gpc.poly-method
> ###   get.bbox,gpc.poly-method get.pts,gpc.poly-method
> ###   intersect,gpc.poly,gpc.poly-method plot,gpc.poly-method
> ###   scale.poly,gpc.poly-method setdiff,gpc.poly,gpc.poly-method
> ###   show,gpc.poly-method union,gpc.poly,gpc.poly-method
> ###   tristrip,gpc.poly-method triangulate,gpc.poly-method
> ### Keywords: classes
> 
> ### ** Examples
> 
> ## Make some random polygons
> set.seed(100)
> a <- cbind(rnorm(100), rnorm(100))
> a <- a[chull(a), ]
> 
> ## Convert `a' from matrix to "gpc.poly"
> a <- as(a, "gpc.poly")
> 
> b <- cbind(rnorm(100), rnorm(100))
> b <- as(b[chull(b), ], "gpc.poly")
> 
> ## More complex polygons with an intersection
> p1 <- read.polyfile(system.file("poly-ex/ex-poly1.txt", package = "gpclib"))
> p2 <- read.polyfile(system.file("poly-ex/ex-poly2.txt", package = "gpclib"))
> 
> ## Plot both polygons and highlight their intersection in red
> plot(append.poly(p1, p2))
> plot(intersect(p1, p2), poly.args = list(col = 2), add = TRUE)
> 
> ## Highlight the difference p1 \ p2 in green
> plot(setdiff(p1, p2), poly.args = list(col = 3), add = TRUE)
> 
> ## Highlight the difference p2 \ p1 in blue
> plot(setdiff(p2, p1), poly.args = list(col = 4), add = TRUE)
> 
> ## Plot the union of the two polygons
> plot(union(p1, p2))
Error in h(simpleError(msg, call)) : 
  error in evaluating the argument 'x' in selecting a method for function 'plot': DLL requires the use of native symbols
Calls: plot -> union -> union -> .handleSimpleError -> h
Execution halted