Cut a Coastline Object at Specified Longitude

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

a coastline object.

lon_0

longitude as would be given in a +lon_0= item in a call to sf::sf_project().

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.

See also

Other things related to coastline data: [[,coastline-method, [[<-,coastline-method, as.coastline(), coastline-class, coastlineBest(), coastlineWorld, download.coastline(), plot,coastline-method, read.coastline.openstreetmap(), read.coastline.shapefile(), subset,coastline-method, summary,coastline-method

Author

Dan Kelley

Examples

# \donttest{
library(oce)
data(coastlineWorld)
mapPlot(coastlineCut(coastlineWorld, lon_0 = 100),
    projection = "+proj=moll +lon_0=100", col = "gray"
)

# }