[R-sig-Geo] Determine if a line segment intersects a polygon

[GREGOR Brian J]

> I am looking for a method that would determine whether any part of a
> line segment defined by (x0, y0) and (x1, y1) intersects a 
> given polygon
> (true or false).  I don't have any other geospatial needs 
> here, so if a
> solution exists using base R that would be great.

I had to do something similar and used the "crossing.psp" function in
the "spatstat" package. It determines the crossing points of two sets of
line segments. You will need to convert the line segments describing the
polygon boundary into a line segment pattern of class "psp" used by
"spatstat".

Brian Gregor, P.E.
Transportation Planning Analysis Unit
Oregon Department of Transportation
Brian.J.GREGOR at odot.state.or.us
(503) 986-4120