clipLines: Clip a PolySet as Polylines

Description Usage Arguments Details Value Author(s) See Also Examples

View source: R/PBSmapping.r

Description

Clip a PolySet, where each unique (PID, SID) describes a polyline.

Usage

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clipLines (polys, xlim, ylim, keepExtra = FALSE)

Arguments

polys

PolySet to clip.

xlim

range of X-coordinates.

ylim

range of Y-coordinates.

keepExtra

Boolean value; if TRUE, tries to carry forward any non-standard columns into the result.

Details

For each discrete polyline, the function does not connect vertices 1 and N. It recalculates the POS values for each vertex, saving the old values in a column named oldPOS. For new vertices, it sets oldPOS to NA.

Value

PolySet containing the input data, with some points added or removed. A new column oldPOS records the original POS value for each vertex.

Author(s)

Nicholas M. Boers, Associate Professor – Computer Science
MacEwan University, Edmonton AB
Last modified Rd: 2013-04-10

See Also

clipPolys, fixBound.

Examples

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local(envir=.PBSmapEnv,expr={
  oldpar = par(no.readonly=TRUE)
  #--- create a triangle to clip
  polys <- data.frame(PID=rep(1, 3), POS=1:3, X=c(0,1,0), Y=c(0,0.5,1))
  #--- clip the triangle in the X direction, and plot the results
  plotLines(clipLines(polys, xlim=c(0,.75), ylim=range(polys[, "Y"])))
  par(oldpar)
})

PBSmapping documentation built on Jan. 15, 2021, 3:41 p.m.