RArcInfo              package:RArcInfo              R Documentation

_R_A_r_c_I_n_f_o

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

     This package allows the user to import into R binary coverages in
     format Arc/Info V 7.x. These coverages represent geographical data
     in several forms: points, lines, polygons, point labels, etc. 

     RArcInfo uses the library AVCE00, written by Daniel Morissette, to
     whom I would thank fo his marvelous work. But RArcInfo is much
     more than a wrapper of this library, because it provides functions
     to plot the data and draw maps.

     Since the geographical data are separated into several files,
     RArcInfo provides a different  function to read each file. These
     functions are called get.XXXdata, where XXX is the file name to
     open (usually the extension is 'adf'):

     *  get.arcdata

        ARC files contain arcs definition and their vertices.

     *  get.bnddata

        BND files contain coordinates for the boundary of the data.

     *  get.cntdata

        CNT files contain polygon centroid information.

     *  get.labdata

        LAB files contain label point records.

     *  get.paldata

        PAL files contain the polygon definitions.

     *  get.toldata

        TOL files contain the tolerance values that were used when
        processing the polygon coverage.

     *  get.txtdata

        TXT files contain annotations (or labels) about the data.

        Besides these files, binary coverage store several tables
        containing additional information (like name of the city,
        population, etc.). To get this data, RArcInfo provides the next
        functions:

     *  get.tablenames 

        Gets all the table names and the coverage each table belongs
        to.

     *  get.tablefields

        Gets the names of the fields for a given table.

     *  get.tabledata

        Gets the data stored in the table.

        In order to plot the data, RArcInfo has several functions:

     *  plotarc

        Plots all the arcs.

     *  plotpal

        Plots all the polygons.

     *  plotpoly

        Like plotpal, but it allows to select the polygons we want to
        plot, colour and  other stuff. This is useful to plot maps
        according the value of some covariate.

        To get all the names of the coverages, the user can call
        'get.namesofcoverages'.

        Other two interesting functions are:

     *  thinlines

        Useful to reduce the number of points in an arc according to a
        given tolerance.

     *  get.nb

        Calculates the neighbouring polygons of a given set of
        polygons.

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

     More information about this kind of data can be found at <URL:
     http://pages.infinit.net/danmo/e00/docs/v7_bin_cover.html>.

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

     get.arcdata, get.bnddata, get.cntdata, get.labdata, get.paldata,
     get.toldata, get.txtdata, get.tablenames, get.tablefields,
     get.tabledata, get.namesofcoverages, read.coverage, thinlines,
     get.nb

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

     library(RArcInfo)

     datadir<-system.file("exampleData",package="RArcInfo")
     infodir<-system.file("exampleData","info",package="RArcInfo")
     coveragedir<-system.file("exampleData","wetlands",package="RArcInfo")

     #get.bnddata needs the last slash...
     infodir<-paste(c(infodir,"/"), collapse="")

     #List all the tables

     covnames<-get.namesofcoverages(datadir)
     tablenames<-get.tablenames(infodir)

     #Display the name of the table and its filds
     for(i in 1:length(tablenames[[1]]))
     {
             print(c("Table: ",tablenames$TableName[i]))

             fields<-get.tablefields(infodir,tablenames$TableName[i])
             print("Fields")
             for(j in 1:length(fields))
                     print(fields[[j]][1])

             #Get the data
             if(i==1)
                     tabledata<-get.tabledata(infodir,tablenames$TableName[i])
             else
                     tabledata<-c(tabledata, get.tabledata(infodir,tablenames$TableName[i]) )
     }

     #Import data fromsome tables
     arc<-get.arcdata(datadir,"wetlands")
     pal<-get.paldata(datadir,"wetlands")
     lab<-get.labdata(datadir,"wetlands")
     cnt<-get.cntdata(datadir,"wetlands")

     bnd<-get.bnddata(infodir,"WETLANDS.BND")

     print("Plotting all the arcs")
     plotarc(arc)

     print("Plotting the first ten polygons (in red) on the previous plot")
     par(col="red")
     plotpal(arc,pal,new=FALSE, index=1:10)

