注意：在 Edzer Pebesma 的建议下，这个问题已被交叉发布到 R-sig-geo，在这里，它得到了一些很好的回应。
我遇到了以下意外结果checkPolygonsHoles：
# attach the worldmap as SpatialPolygonsDataFrame from the package maptools
library(sp)
library(maptools)
data(wrld_simpl)
# get a polygon with a hole
shape_with_hole <- wrld_simpl[5,]
# plot it (hole is left white, surrounded by blue color)
plot(shape_with_hole, col = "blue")
# perform checkPolygonsHoles
shape_with_hole@polygons <- lapply(shape_with_hole@polygons, checkPolygonsHoles)
# plot again, now holes aren't recognized as such
plot(shape_with_hole, col = "blue")
# and even the original SpatialPolygonsDataFrame object is changed !?
plot(wrld_simpl[5,], col = "blue")
这里一个恼人的副作用是原始对象wrld_simpl也被改变了。这个结果在我看来就像一个错误，还是我错过了什么？
PS：之前shape_with_hole编辑的对象checkPolygonsHoles，继续表现奇怪：
# we check which polygons are marked as holes. The flags are still set
# properly, although the `plot` function didn't recognize them:
sapply(shape_with_hole@polygons[[1]]@Polygons, slot, "hole")
[1] FALSE TRUE TRUE TRUE
# load library rgdal for reprojection
library(rgdal)
# reproject with `spTransform`, just for testing
shape_with_hole <- spTransform(shape_with_hole,
CRS("+proj=longlat +ellps=WGS84 +datum=WGS84"))
# after reprojection all flags are set to FALSE
sapply(shape_with_hole@polygons[[1]]@Polygons, slot, "hole")
[1] FALSE FALSE FALSE FALSE