R:子集化和绘制 SpatialPoints 对象
R: Subsetting and plotting a SpatialPoints object
这个问题似乎已经以不同的形式被问过几次,但我找不到正确的解决方案。我有一个带有多个多边形的 SpatialPoint 对象,我想使用插槽 "ID".
子集和绘制 one 多边形
使用 this 问题中的示例:
Sr1 = Polygon(cbind(c(2,4,4,1,2),c(2,3,5,4,2)))
Sr2 = Polygon(cbind(c(5,4,2,5),c(2,3,2,2)))
Sr3 = Polygon(cbind(c(4,4,5,10,4),c(5,3,2,5,5)))
SpP = SpatialPolygons(list(Srs1,Srs2,Srs3), 1:3)
我可以提取 SpatialPolygons 对象的 ID
SpP@polygons[[1]]@ID # one ID
sapply(SpP@polygons, function(x) x@ID) # all IDs
但是我如何使用这些信息来划分和绘制一个多边形?很高兴得到任何帮助,在此先感谢!
可以使用 []
进行子集化。请参阅 SpatialPolygons-class 帮助 (?'SpatialPolygons-class'
):
Methods [...]:
[ : select subset of (sets of) polygons; NAs are not permitted in the row index"
因此使用您的数据:
library(sp)
Sr1 = Polygon(cbind(c(2,4,4,1,2),c(2,3,5,4,2)))
Sr2 = Polygon(cbind(c(5,4,2,5),c(2,3,2,2)))
Sr3 = Polygon(cbind(c(4,4,5,10,4),c(5,3,2,5,5)))
Sr4 = Polygon(cbind(c(5,6,6,5,5),c(4,4,3,3,4)), hole = TRUE)
Srs1 = Polygons(list(Sr1), "s1")
Srs2 = Polygons(list(Sr2), "s2")
Srs3 = Polygons(list(Sr3, Sr4), "s3/4")
SpP = SpatialPolygons(list(Srs1,Srs2,Srs3), 1:3)
# plot single polygon
par(mfrow=c(3,1))
plot(SpP[1])
plot(SpP[3])
# or using IDs: retrieve list of all IDs
IDs = sapply(SpP@polygons, function(x) x@ID)
# plot polygon with specific ID
plot(SpP[which(IDs == 's2')])
这个问题似乎已经以不同的形式被问过几次,但我找不到正确的解决方案。我有一个带有多个多边形的 SpatialPoint 对象,我想使用插槽 "ID".
子集和绘制 one 多边形使用 this 问题中的示例:
Sr1 = Polygon(cbind(c(2,4,4,1,2),c(2,3,5,4,2)))
Sr2 = Polygon(cbind(c(5,4,2,5),c(2,3,2,2)))
Sr3 = Polygon(cbind(c(4,4,5,10,4),c(5,3,2,5,5)))
SpP = SpatialPolygons(list(Srs1,Srs2,Srs3), 1:3)
我可以提取 SpatialPolygons 对象的 ID
SpP@polygons[[1]]@ID # one ID
sapply(SpP@polygons, function(x) x@ID) # all IDs
但是我如何使用这些信息来划分和绘制一个多边形?很高兴得到任何帮助,在此先感谢!
可以使用 []
进行子集化。请参阅 SpatialPolygons-class 帮助 (?'SpatialPolygons-class'
):
Methods [...]:
[ : select subset of (sets of) polygons; NAs are not permitted in the row index"
因此使用您的数据:
library(sp)
Sr1 = Polygon(cbind(c(2,4,4,1,2),c(2,3,5,4,2)))
Sr2 = Polygon(cbind(c(5,4,2,5),c(2,3,2,2)))
Sr3 = Polygon(cbind(c(4,4,5,10,4),c(5,3,2,5,5)))
Sr4 = Polygon(cbind(c(5,6,6,5,5),c(4,4,3,3,4)), hole = TRUE)
Srs1 = Polygons(list(Sr1), "s1")
Srs2 = Polygons(list(Sr2), "s2")
Srs3 = Polygons(list(Sr3, Sr4), "s3/4")
SpP = SpatialPolygons(list(Srs1,Srs2,Srs3), 1:3)
# plot single polygon
par(mfrow=c(3,1))
plot(SpP[1])
plot(SpP[3])
# or using IDs: retrieve list of all IDs
IDs = sapply(SpP@polygons, function(x) x@ID)
# plot polygon with specific ID
plot(SpP[which(IDs == 's2')])