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Download a coastline File

Source: R/coastline.R
download.coastline.Rd

Constructs a query to the NaturalEarth server (see reference 1) to download coastline data (or lake data, river data, etc) in any of three resolutions.

Usage

download.coastline(
  resolution,
  item = "coastline",
  destdir = ".",
  destfile,
  server = "naturalearth",
  debug = getOption("oceDebug")
)

Arguments

resolution

A character value specifying the desired resolution. The permitted choices are "10m" (for 1:10M resolution, the most detailed), "50m" (for 1:50M resolution) and "110m" (for 1:110M resolution). If resolution is not supplied, "50m" will be used.

item

A character value indicating the quantity to be downloaded. This is normally one of "coastline", "land", "ocean", "rivers_lakes_centerlines", or "lakes", but the NaturalEarth server has other types, and advanced users can discover their names by inspecting the URLs of links on the NaturalEarth site, and use them for item. If item is not supplied, it defaults to "coastline".

destdir

Optional string indicating the directory in which to store downloaded files. If not supplied, "." is used, i.e. the data file is stored in the present working directory.

destfile

Optional string indicating the name of the file. If not supplied, the file name is constructed from the other parameters of the function call, so subsequent calls with the same parameters will yield the same result, thus providing the key to the caching scheme.

server

A character value specifying the server that is to supply the data. At the moment, the only permitted value is "naturalearth", which is the default if server is not supplied.

debug

an integer specifying whether debugging information is to be printed during the processing. This is a general parameter that is used by many oce functions. Generally, setting debug=0 turns off the printing, while higher values suggest that more information be printed. If one function calls another, it usually reduces the value of debug first, so that a user can often obtain deeper debugging by specifying higher debug values.

Value

A character value indicating the filename of the result; if there is a problem of any kind, the result will be the empty string.

Non-Executable Examples


library(oce)
# User must create directory ~/data/coastline first.
# As of September 2016, the downloaded file, named
# "ne_50m_coastline.zip", occupies 443K bytes.
filename <- download.coastline(destdir="~/data/coastline")
coastline <- read.coastline(filename)
plot(coastline)

References

  1. The NaturalEarth server is at https://www.naturalearthdata.com

See also

The work is done with utils::download.file().

Other functions that download files: download.amsr(), download.met(), download.topo()

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

Author

Dan Kelley