rgdal (version 0.6-9)

readOGR: Read OGR vector maps into Spatial objects

Description

The function reads an OGR data source and layer into a suitable Spatial vector object. It can only handle layers with conformable geometry features (not mixtures of points, lines, or polygons in a single layer). It will set the spatial reference system if the layer has such metadata.

Usage

readOGR(dsn, layer, verbose = TRUE, p4s=NULL, drop_unsupported_fields=FALSE,
 input_field_name_encoding=NULL, pointDropZ=FALSE, dropNULLGeometries=TRUE)
ogrInfo(dsn, layer, input_field_name_encoding=NULL)
ogrFIDs(dsn, layer)
ogrDrivers()
## S3 method for class 'ogrinfo':
print(x, ...)

Arguments

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)

verbose

report progress

p4s

PROJ4 string defining CRS, if default NULL, the value is read from the OGR data set

drop_unsupported_fields

default FALSE, if TRUE skip fields other than String, Integer, and Real; Date, Time and DateTime are converted to String

input_field_name_encoding

default NULL; if not NULL, should be a valid encoding name for the source platform of the data source and layer, see iconv

pointDropZ

default FALSE, if TRUE, discard third coordinates for point geometries; third coordinates are alway discarded for line and polygon geometries

dropNULLGeometries

default TRUE, drop both declared NULL geometries, and empty geometries with no coordinates; if FALSE, return a data frame with the attribute values of the NULL and empty geometries

x

ogrinfo object

...

other arguments to print method

Value

• A Spatial object is returned suiting the vector data source, either a SpatialPointsDataFrame (using an AttributeList for its data slot directly), a SpatialLinesDataFrame, or a SpatialPolygonsDataFrame.

Details

The drivers available will depend on the installation of GDAL/OGR, and can vary; the ogrDrivers() function shows which are available, and which may be written (but all are assumed to be readable). Note that stray files in data source directories (such as *.dbf) may lead to suprious errors that accompanying *.shp are missing.

References

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

See Also

SpatialPointsDataFrame-class, SpatialLinesDataFrame-class, SpatialPolygonsDataFrame-class, readShapePoly, iconv

Examples

ogrDrivers()
ogrInfo(system.file("vectors", package = "rgdal")[1], "cities")
cities <- readOGR(system.file("vectors", package = "rgdal")[1], "cities")
summary(cities)
ogrInfo(system.file("vectors", package = "rgdal")[1], "kiritimati_primary_roads")
kiritimati_primary_roads <- readOGR(system.file("vectors", package = "rgdal")[1], "kiritimati_primary_roads")
summary(kiritimati_primary_roads)
ogrInfo(system.file("vectors", package = "rgdal")[1], "scot_BNG")
scot_BNG <- readOGR(system.file("vectors", package = "rgdal")[1], "scot_BNG")
summary(scot_BNG)
if ("GML" %in% ogrDrivers()$name) {
  airports <- try(readOGR(system.file("vectors/airports.gml", package = "rgdal")[1], "airports"))
  if (class(airports) != "try-error") summary(airports)
}
ogrInfo(system.file("vectors/ps_cant_31.MIF", package = "rgdal")[1], "ps_cant_31")
ps_cant_31 <- readOGR(system.file("vectors/ps_cant_31.MIF", package = "rgdal")[1], "ps_cant_31")
summary(ps_cant_31)
ogrInfo(system.file("vectors/Up.tab", package = "rgdal")[1], "Up")
Up <- readOGR(system.file("vectors/Up.tab", package = "rgdal")[1], "Up")
summary(Up)
test_trk2 <- try(readOGR(system.file("vectors/test_trk2.gpx", package = "rgdal")[1], "tracks"))
if (class(test_trk2) != "try-error") summary(test_trk2)
test_trk2pts <- try(readOGR(system.file("vectors/test_trk2.gpx", package = "rgdal")[1], "track_points"))
if (class(test_trk2pts) != "try-error") summary(test_trk2pts)
ogrInfo(system.file("vectors", package = "rgdal")[1], "trin_inca_pl03")
birds <- readOGR(system.file("vectors", package = "rgdal")[1], "trin_inca_pl03")
summary(birds)