readOGR                package:rgdal                R Documentation

_R_e_a_d _O_G_R _v_e_c_t_o_r _m_a_p_s _i_n_t_o _S_p_a_t_i_a_l _o_b_j_e_c_t_s

_D_e_s_c_r_i_p_t_i_o_n:

     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.

_U_s_a_g_e:

     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, ...)

_A_r_g_u_m_e_n_t_s:

     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

_D_e_t_a_i_l_s:

     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.

_V_a_l_u_e:

     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.

_N_o_t_e:

     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.

     Please note that the OGR drivers used may not handle missing data
     gracefully, and be prepared to have to correct for this manually.
     From rgdal 0.5-27, missing value handling has been improved, and
     OGR unset field values are set to NA in R, but drivers and
     external files may vary in their representations of missing
     values.

_A_u_t_h_o_r(_s):

     Roger Bivand

_R_e_f_e_r_e_n_c_e_s:

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

_S_e_e _A_l_s_o:

     'SpatialPointsDataFrame-class', 'SpatialLinesDataFrame-class',
     'SpatialPolygonsDataFrame-class', 'readShapePoly'

_E_x_a_m_p_l_e_s:

     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)

