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, clip.AN=TRUE)
Arguments
polys |
|
xlim |
|
ylim |
|
clip.AN |
|
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.
Note
The Antarctic polygon is treated as a special case in that it is expanded longitudinally
by duplicating it to the West and East of the base polygon. The expanded Antarctica is
then clipped to the limits of the plot, or not if 'clip.NA=FALSE'
.
Author(s)
Nicholas M. Boers, Staff Software Engineer
Jobber, Edmonton AB
Rowan Haigh, Program Head – Offshore Rockfish
Pacific Biological Station (PBS), Fisheries & Oceans Canada (DFO), Nanaimo BC
locus opus: Institute of Ocean Sciences (IOS), Sidney BC
Last modified Rd: 2018-10-26
See Also
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)
})