readShapePoints           package:maptools           R Documentation

_R_e_a_d _p_o_i_n_t_s _s_h_a_p_e _f_i_l_e_s _i_n_t_o _S_p_a_t_i_a_l_P_o_i_n_t_s_D_a_t_a_F_r_a_m_e _o_b_j_e_c_t_s

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

     The 'readShapePoints' reads data from a points shapefile into a
     'SpatialPointsDataFrame' object. The 'writePointsShape' function
     writes data from a 'SpatialPointsDataFrame' object to a shapefile.
     Both reading and writing can be carried out for 2D and 3D point
     coordinates.

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

     readShapePoints(fn, proj4string = CRS(as.character(NA)), verbose = FALSE,
      repair=FALSE)
     writePointsShape(x, fn, factor2char = TRUE, max_nchar=254)

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

      fn: shapefile layer name, when writing omitting the extensions
          *.shp, *.shx and *.dbf, which are added in the function

proj4string: Object of class 'CRS'; holding a valid proj4 string

 verbose: default TRUE - report type of shapefile and number of shapes

  repair: default FALSE: some shapefiles provided by Geolytics Inc.
          have values of object sizes stored in the *.shx index file
          that are eight bytes too large, leading the function to try
          to read past the end of file. If repair=TRUE, an attempt is
          made to repair the internal values, permitting such files to
          be read.

       x: a 'SpatialPointsDataFrame' object

factor2char: logical, default TRUE, convert factor columns to character

max_nchar: default 254, may be set to a higher limit and passed through
          to the DBF writer, please see Details in 'write.dbf'

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

     a SpatialPointsDataFrame object

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

     Roger Bivand

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

     library(maptools)
     xx <- readShapePoints(system.file("shapes/baltim.shp", package="maptools")[1])
     plot(xx)
     summary(xx)
     xxx <- xx[xx$PRICE < 40,]
     tmpfl <- paste(tempdir(), "xxpts", sep="/")
     writePointsShape(xxx, tmpfl)
     getinfo.shape(paste(tmpfl, ".shp", sep=""))
     axx <- readShapePoints(tmpfl)
     plot(axx, col="red", add=TRUE)
     unlink(paste(tmpfl, ".*", sep=""))
     xx <- readShapePoints(system.file("shapes/pointZ.shp", package="maptools")[1])
     dimensions(xx)
     plot(xx)
     summary(xx)

