ContourLines2SLDF          package:maptools          R Documentation

_C_o_n_v_e_r_t_e_r _f_u_n_c_t_i_o_n_s _t_o _b_u_i_l_d _S_p_a_t_i_a_l_L_i_n_e_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:

     These functions show how to build converters to
     SpatialLinesDataFrame objects:  'ArcObj2SLDF' from the list
     returned by the 'get.arcdata' function in the RArcInfo package;
     'ContourLines2SLDF' from the list returned by the 'contourLines'
     function in the graphics package (here the data frame is just the
     contour levels, with one Lines object made up of at least one Line
     object per level); and 'MapGen2SL' reads a file in "Mapgen" format
     into a 'SpatialLines' object.

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

     ArcObj2SLDF(arc, proj4string=CRS(as.character(NA)), IDs)
     ContourLines2SLDF(cL, proj4string=CRS(as.character(NA)))
     MapGen2SL(file, proj4string=CRS(as.character(NA)))

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

     arc: a list returned by the 'get.arcdata' function in the RArcInfo
          package

     IDs: vector of unique character identifiers; if not given,
          suitable defaults will be used, and the same values inserted
          as data slot row names

      cL: a list returned by the 'contourLines' function in the
          graphics package

proj4string: Object of class '"CRS"'; see CRS-class

    file: filename of a file containing a Mapgen line data set

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

     A SpatialLinesDataFrame object

_N_o_t_e:

     Coastlines of varying resolution may be chosen online and
     downloaded in "Mapgen" text format from <URL:
     http://www.ngdc.noaa.gov/mgg/shorelines/shorelines.html>, most
     conveniently using the interactive selection tool, but please note
     the 500,000 point limit on downloads, which is easy to exceed.

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

     Roger Bivand; Edzer Pebesma

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

     SpatialLines-class

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

     #data(co37_d90_arc) # retrieved as: 
     # library(RArcInfo)
     # fl <- "http://www.census.gov/geo/cob/bdy/co/co90e00/co37_d90_e00.zip"
     # download.file(fl, "co37_d90_e00.zip")
     # e00 <- zip.file.extract("co37_d90.e00", "co37_d90_e00.zip")
     # e00toavc(e00, "ncar")
     # arc <- get.arcdata(".", "ncar")
     #res <- arcobj2SLDF(arc)
     #plot(res)
     #invisible(title(""))
     res <- ContourLines2SLDF(contourLines(volcano))
     plot(res, col=terrain.colors(nrow(as(res, "data.frame"))))
     title("Volcano contours as SpatialLines")

