R: Cut a Coastline Object at Specified Longitude

coastlineCut {oce} | R Documentation

## 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 project 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.

### 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`

### Examples

    library(oce)
    data(coastlineWorld)
    ## Not run:
    mapPlot(coastlineCut(coastlineWorld, lon_0=100), proj="+proj=robin +lon_0=100")#, col='gray')

    ## End(Not run)

[Package oce version 0.9-20 Index]