RArcInfo: RArcInfo
In RArcInfo: Functions to import data from Arc/Info V7.x binary coverages

Description References See Also Examples

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.

V. G<f3>mez-Rubio and A. L<f3>pez-Qu<ed>lez (2005). RArcInfo: Using GIS data with R. Computers & Geosciences 3(8), 1000-1006.

More information about this kind of data can be found at http://avce00.maptools.org/docs/v7_bin_cover.html.

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

#See example(plotpoly) for another example

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 fields
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 from some 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)