coastlineCut: Cut a Coastline Object at Specified Longitude
Description
This can be helpful in preventing mapPlot from producing ugly
horizontal lines in world maps. These lines occur when a coastline segment
is intersected by longitude lon_0+180. Since the coastline files in the oce
and ocedata packages are already "cut" at longitudes of -180 and 180, the present
function is not needed for default maps, which have +lon_0=0. However,
may help with other values of lon_0.
Usage
coastlineCut(coastline, lon_0 = 0)
Arguments
coastline
original coastline object
lon_0
longitude as would be given in a +lon_0= item in a
call to the project function in the
rgdal package.
Value
a new coastline object
Caution
This function is provisional. Its behaviour, name and very existence
may change. Part of the development plan is to see if there is common
ground between this and the clipPolys function in the
PBSmapping package.
# NOT RUN {library(oce)
data(coastlineWorld)
mapPlot(coastlineCut(coastlineWorld, lon_0=100),
proj="+proj=moll +lon_0=100", col='gray')
# }# NOT RUN {# }