ContourLines2SLDF: Converter functions to build SpatialLinesDataFrame objects

In maptools: Tools for Handling Spatial Objects

Converter functions to build SpatialLinesDataFrame objects

Description

These functions show how to build converters to SpatialLinesDataFrame objects: ArcObj2SLDF from the list returned by the get.arcdata function in the RArcInfo package; ContourLines2SLDF from the list returned by the contourLines function in the graphics package (here the data frame is just the contour levels, with one Lines object made up of at least one Line object per level); and MapGen2SL reads a file in "Mapgen" format into a SpatialLines object.

Usage

ArcObj2SLDF(arc, proj4string=CRS(as.character(NA)), IDs)
ContourLines2SLDF(cL, proj4string=CRS(as.character(NA)))
MapGen2SL(file, proj4string=CRS(as.character(NA)))

Arguments

arc	a list returned by the get.arcdata function in the RArcInfo package
IDs	vector of unique character identifiers; if not given, suitable defaults will be used, and the same values inserted as data slot row names
cL	a list returned by the contourLines function in the graphics package
proj4string	Object of class "CRS"; see CRS-class
file	filename of a file containing a Mapgen line data set

Value

A SpatialLinesDataFrame object

Note

Coastlines of varying resolution may be chosen online and downloaded in "Mapgen" text format from https://www.ngdc.noaa.gov/mgg/shorelines/shorelines.html, most conveniently using the interactive selection tool, but please note the 500,000 point limit on downloads, which is easy to exceed.

Author(s)

Roger Bivand; Edzer Pebesma

See Also

SpatialLines-class

Examples

#data(co37_d90_arc) # retrieved as: 
# library(RArcInfo)
# fl <- "http://www.census.gov/geo/cob/bdy/co/co90e00/co37_d90_e00.zip"
# download.file(fl, "co37_d90_e00.zip")
# e00 <- zip.file.extract("co37_d90.e00", "co37_d90_e00.zip")
# e00toavc(e00, "ncar")
# arc <- get.arcdata(".", "ncar")
#res <- arcobj2SLDF(arc)
#plot(res)
#invisible(title(""))
res <- ContourLines2SLDF(contourLines(volcano))
plot(res, col=terrain.colors(nrow(as(res, "data.frame"))))
title("Volcano contours as SpatialLines")

maptools documentation built on July 26, 2023, 5:38 p.m.