Convert Polylines into a Polygon
Convert two polylines into a polygon.
convLP (polyA, polyB, reverse = TRUE)
The resulting PolySet contains all the vertices from
polyA in their original order. If reverse = TRUE, this
function appends the vertices from polyB in the reverse order
(nrow(polyB):1). Otherwise, it appends them in their original
order. The PID column equals the PID of polyA.
No SID column appears in the result. The resulting polygon is
an exterior boundary.
PolySet with a single PID that is the same as
polyA. The result contains all the vertices in polyA and
polyB. It has the same projection and zone
attributes as those in the input PolySets. If an input PolySet's
attributes equal NULL, the function uses the other
PolySet's. If the PolySet attributes conflict, the result's attribute
equals NULL.
Nicholas M. Boers, Associate Professor – Computer Science
MacEwan University, Edmonton AB
Last modified Rd: 2013-04-10
local(envir=.PBSmapEnv,expr={
oldpar = par(no.readonly=TRUE)
#--- create two polylines
polyline1 <- data.frame(PID=rep(1,2),POS=1:2,X=c(1,4),Y=c(1,4))
polyline2 <- data.frame(PID=rep(1,2),POS=1:2,X=c(2,5),Y=c(1,4))
#--- create two plots to demonstrate the effect of `reverse'
par(mfrow=c(2, 1))
plotPolys(convLP(polyline1, polyline2, reverse=TRUE), col=2)
plotPolys(convLP(polyline1, polyline2, reverse=FALSE), col=3)
par(oldpar)
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