PBSmapping (version 2.72.1)

refocusWorld: 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, clip.AN=TRUE)

Arguments

polys

PolySet -- object with one or more polygons; typically worldLL or worldLLhigh (required).

xlim

numeric -- range of X-coordinates.

ylim

numeric -- range of Y-coordinates.

clip.AN

logical -- if TRUE, clip expanded Antarctica to 'xlim' of refocused polygons other than Antarctica and to user-defined/default 'ylim'.

Value

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

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.

See Also

joinPolys

Examples

# NOT RUN {
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)
})
# }