convLP function

Convert Polylines into a Polygon

Convert two polylines into a polygon.

convLP (polyA, polyB, reverse = TRUE)

Arguments

• polyA: PolySet containing a polyline.
• polyB: PolySet containing a polyline.
• reverse: Boolean value; if TRUE, reverse polyB's vertices.

Details

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.

Returns

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.

Author(s)

Nicholas M. Boers, Staff Software Engineer

Jobber, Edmonton AB

Last modified Rd: 2013-04-10

See Also

addLines, appendPolys, closePolys, convCP, joinPolys, plotLines.

Examples

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)
})