rgdal (version 0.7-7)

writeOGR: Write spatial vector data using OGR

Description

The function is an interface with the OGR abstraction library for spatial vector data, allowing data to be written out using supported drivers. The drivers supported will depend on the local installation, and the capabilities of those drivers (many are read-only). The objects exported are SpatialPointsDataFrame, SpatialLinesDataFrame, or SpatialPolygonsDataFrame objects as defined in the sp package.

Usage

writeOGR(obj, dsn, layer, driver, dataset_options = NULL,
 layer_options=NULL, verbose = FALSE, check_exists=NULL, overwrite_layer=FALSE, delete_dsn=FALSE)

Arguments

obj

a SpatialPointsDataFrame, SpatialLinesDataFrame, or a SpatialPolygonsDataFrame object.

dsn

data source name (interpretation varies by driver --- for some drivers, dsn is a file name, but may also be a folder)

layer

layer name (varies by driver, may be a file name without extension)

driver

a character string equal to one of the driver names returned by ogrDrivers

dataset_options

a character vector of options, which vary by driver, and should be treated as experimental

layer_options

a character vector of options, which vary by driver, and should be treated as experimental

verbose

if TRUE, returns a list of information about the attempted write operation

check_exists

default NULL, which tests for the GDAL version, and sets FALSE if < 1.8.0, or TRUE for >= 1.8.0

overwrite_layer

default FALSE, if TRUE and check_exists=TRUE, delete the existing layer of the same name from the data source before writing the new layer; this will delete data and must be used with extreme caution, its behaviour varies between drivers, and

delete_dsn

default FALSE, may be set to TRUE if overwrite_layer reports that the data source cannot be updated; this will delete data and must be used with extreme caution, its behaviour varies between drivers, and accommodates changes that may appear i

Value

• if verbose=TRUE, a list of information about the attempted write operation

Warning

The overwrite_layer and delete_dsn arguments are provided only for experienced script writers who need to be able to destroy data, for example during repetetive simulation runs. They should never be used by anyone who is not confident about deleting files.

Details

Working out which combination of dsn, layer, and driver (and option) values give the desired output takes time and care, and is constrained by the ability of drivers to write output; many are read-only. Use of the references given is highly advisable, with searches in the archives of other software using GDAL/OGR.

References

http://www.gdal.org/ogr/, http://www.gdal.org/ogr/ogr_formats.html, http://examples.oreilly.com/webmapping/

See Also

readOGR

Examples

cities <- readOGR(system.file("vectors", package = "rgdal")[1], "cities")
is.na(cities$POPULATION) <- cities$POPULATION == -99
summary(cities$POPULATION)
td <- tempdir()
if(nchar(Sys.getenv("OSGEO4W_ROOT") > 0)) {
    OLDPWD <- getwd()
    setwd(td)
    td <- "."
}
writeOGR(cities, td, "cities", driver="ESRI Shapefile")
cities2 <- readOGR(td, "cities")
summary(cities2$POPULATION)
all.equal(cities, cities2)
if ("GML" %in% ogrDrivers()$name) {
  airports <- try(readOGR(system.file("vectors/airports.gml",
    package = "rgdal")[1], "airports"))
  if (class(airports) != "try-error") {
    writeOGR(cities, paste(td, "cities.gml", sep="/"), "cities", driver="GML")
    cities3 <- readOGR(paste(td, "cities.gml", sep="/"), "cities")
    all.equal(cities, cities3)
  }
}
# The GML driver does not support coordinate reference systems
if ("KML" %in% ogrDrivers()$name) {
  data(meuse)
  coordinates(meuse) <- c("x", "y")
  proj4string(meuse) <- CRS("+init=epsg:28992")
  meuse_ll <- spTransform(meuse, CRS("+proj=longlat +datum=WGS84"))
  writeOGR(meuse_ll["zinc"], paste(td, "meuse.kml", sep="/"), "zinc", "KML")
}
list.files(td)
roads <- readOGR(system.file("vectors", package = "rgdal")[1],
 "kiritimati_primary_roads")
summary(roads)
writeOGR(roads, td, "roads", driver="MapInfo File")
roads2 <- readOGR(paste(td, "roads.tab", sep="/"), "roads")
summary(roads2)
scot_BNG <- readOGR(system.file("vectors", package = "rgdal")[1], "scot_BNG")
summary(scot_BNG)
writeOGR(scot_BNG, td, "scot_BNG", driver="MapInfo File")
list.files(td)
scot_BNG2 <- readOGR(paste(td, "scot_BNG.tab", sep="/"), "scot_BNG")
summary(scot_BNG2)
writeOGR(scot_BNG, td, "scot_BNG", driver="MapInfo File",
 dataset_options="FORMAT=MIF")
list.files(td)
scot_BNG3 <- readOGR(paste(td, "scot_BNG.mif", sep="/"), "scot_BNG")
summary(scot_BNG3)
if(nchar(Sys.getenv("OSGEO4W_ROOT") > 0)) {
    setwd(OLDPWD)
}