oce (version 0.2-1)

read.coastline: Scan a coastline data file

Description

Read a coastline file in mapgen, matlab, or Splus format

Usage

read.coastline(file, type=c("R","S","mapgen","shapefile"),
  debug=getOption("oceDebug"), monitor=FALSE, history)
read.coastline.shapefile(file, lonlim=c(-180,180), latlim=c(-90,90),
  debug=getOption("oceDebug"), monitor=FALSE, history)

Arguments

file

name of file containing coastline data.

type

type of file, one of "R", "S", or "mapgen"

debug

set to TRUE to print information about the header, etc.

latlim

range of (signed) latitudes, used only for shapefiles. Regions that do not intersect this range are skipped.

lonlim

as latlim, but a signed longitude.

monitor

print a dot for every coastline segment read (ignored except for reading "shapefile" type)

history

if provided, the action item to be stored in the log. (Typically only provided for internal calls; the default that it provides is better for normal calls by a user.)

Value

• An object of class "coastline", which is a list containing
• data
  a list containing [object Object],[object Object]
• metadata
  a NULL item that may be used in a future version.
• history
  A history of processing, in the standard oce format.

Details

The S and R formats are identical, and consist of two columns, lon and lat, with land-jump segments separated by lines with two NAs.

The MapGen format is of the form # -b -16.179081 28.553943 -16.244793 28.563330 BUG: the 'arc/info ungenerate' format is not yet understood.

References

The NOAA site http://www.ngdc.noaa.gov/mgg/shorelines/shorelines.html is a good source for coastline data files.

See Also

The generic function read.oce provides an alternative to this. Coastlines may be created from latitude/longitude pairs with as.coastline, summarized with summary.coastline and plotted with plot.coastline.

Examples

library(oce)
cl <- read.coastline("7404.dat")
# If no plot yet:
plot(cl)
# To add to an existing plot:
lines(cl$data$longitude, cl$data$latitude)
# Note: another trick is to do something like the following,
# to get issues of whether longitude is defined in (-180,180)
# or (0,360)
lines(cl$datas$longitude, cl$data$latitude)
lines(cl$data$longitude-360, cl$data$latitude)