R: Refocus the 'worldLL'/'worldLLhigh' Data Sets

refocusWorld {PBSmapping}

R Documentation

Refocus the `worldLL`/`worldLLhigh` Data Sets

Description

Refocus the worldLL/worldLLhigh data sets, e.g., refocus them so that Eastern Canada appears to the west of Western Europe.

Usage

refocusWorld (polys, xlim = NULL, ylim = NULL)

Arguments

`polys`	PolySet with one or more polygons; typically `worldLL` or `worldLLhigh` (required).
`xlim`	range of X-coordinates.
`ylim`	range of Y-coordinates.

Details

This function accepts a PolySet containing one or more polygons with X-coordinates that collectively span approximately 360 degrees. The function effectively joins the PolySet into a cylinder and then splits it at an arbitrary longitude according to the user-specified limits. Modifications in the resulting PolySet are restricted to shifting X-coordinates by +/- multiples of 360 degrees, and instead of clipping polygons, the return value simply omits out-of-range polygons.

Value

PolySet, likely a subset of the input PolySet, which retains the same PID/SID values.

Author(s)

Nicholas Boers, Dept. of Computer Science, Grant MacEwan University, Edmonton AB

Examples

local(envir=.PBSmapEnv,expr={
  oldpar = par(no.readonly=TRUE)
  #--- load appropriate data
  data(worldLL,envir=.PBSmapEnv)
  #--- set limits
  xlim <- c(-100,25)
  ylim <- c(0,90)
  #--- refocus and plot the world
  polys <- refocusWorld(worldLL, xlim, ylim)
  plotMap(polys, xlim, ylim)
  par(oldpar)
})

[Package PBSmapping version 2.69.76 Index]

Refocus the worldLL/worldLLhigh Data Sets