[R-sig-Geo] Split polygon by line

Karl Jarvis karljarvis at nau.edu
Fri Jul 24 02:48:17 CEST 2015

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:

pol = 
line = SpatialLines(list(Lines(list(Line(cbind(c(0,1),c(0.5,0.5)))), 

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")


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/>

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