readOGR {rgdal} | R Documentation |
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.
readOGR(dsn, layer, verbose = TRUE, p4s=NULL, drop_unsupported_fields=FALSE) ogrInfo(dsn, layer) ogrFIDs(dsn, layer) ogrDrivers() ## S3 method for class 'ogrinfo': print(x, ...)
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 |
x |
ogrinfo object |
... |
other arguments to print method |
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, which is not the case - KML is writable but not readable). Note that stray files in data source directories (such as *.dbf) may lead to suprious errors that accompanying *.shp are missing.
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.
The bases for this implementation are taken from functions in Barry Rowlingson's draft Rmap package, and from Radim Blazek's v.in.ogr program in GRASS.
Roger Bivand
http://www.remotesensing.org/gdal/ogr/index.html, http://www.remotesensing.org/gdal/ogr/ogr_formats.html, http://examples.oreilly.com/webmapping/
SpatialPointsDataFrame-class
, SpatialLinesDataFrame-class
, SpatialPolygonsDataFrame-class
, readShapePoly
ogrDrivers() cities <- readOGR(system.file("vectors", package = "rgdal")[1], "cities") summary(cities) ogrInfo(system.file("vectors", package = "rgdal")[1], "cities") kiritimati_primary_roads <- readOGR(system.file("vectors", package = "rgdal")[1], "kiritimati_primary_roads") summary(kiritimati_primary_roads) 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) } ps_cant_31 <- readOGR(system.file("vectors/ps_cant_31.MIF", package = "rgdal")[1], "ps_cant_31") summary(ps_cant_31) Up <- readOGR(system.file("vectors/Up.tab", package = "rgdal")[1], "Up") summary(Up)