[R-sig-Geo] Split polygon by line

[Karl Jarvis]

Hi all,
I'd like to split a single convex polygon into two polygons by a line 
that bisects it, like in this toy example:

library(rgeos)
pol = 
SpatialPolygons(list(Polygons(list(Polygon(cbind(c(0,1,1,0,0),c(0,0,1,1,0)))), 
ID="polygon")))
line = SpatialLines(list(Lines(list(Line(cbind(c(0,1),c(0.5,0.5)))), 
ID="line")))

This gives a square with a horizontal line in the middle. I was hoping 
this would do it:

gUnion(pol, line)

But that just gives an answer similar to "pol" that lacks the line.

Another thought was to convert the polygon to lines, gUnion them, and 
then convert to SpatialPolygon.

pol.sl = as(pol, "SpatialLines")
pol.union = gUnion(pol.sl, line)

The first part works, but I can't think of how to get SpatialLines to 
become SpatialPolygons. There's no method for this:

as(pol.union, "SpatialPolygons")

Thoughts?
Karl

-- 
Karl Jarvis
PhD Candidate
Lab of Landscape Ecology and Conservation Biology, Landscape 
Conservation Initiative
Lab of Conservation Biology and Wildlife Ecology, School of Forestry
Northern Arizona University
karljarvis.wordpress.com <https://karljarvis.wordpress.com/>

	[[alternative HTML version deleted]]