Function for importing the contents of an ARC file into R

Description

This function reads and imports into R the contents of an arcs definition file.

Usage

1
get.arcdata(datadir, coverage, filename="arc.adf")

Arguments

datadir

Directory under which all the coverages and a directory called 'info' are.

coverage

The name of the coverage we want to work with.

filename

The name of the file in the coverage directory that stores the data. By default, it is called 'arc.dat'.

Value

This function returns a list with two elements. The first one is a data frame containing the next fields (by columns):

ArcID

A number that identifies this arc.

ArcUserID

Identifier defined by the user.

FromNode

The node where the arc begins.

ToNode

The node where the arc finishes.

LeftPoly

The number of the polygon that is to the left of the arc.

RightPoly

The number of the polygon that is to the right of the arc.

NVertices

The number of vertices the arc has.

The second element is a list that stores the vertices of the arc. So, each element in this list is also a list of two arrays: the first for the X coordinates and the secod for the Y coordinates.