readshpnw: Read a network from a "SpatialLines" or...

In shp2graph: Convert a SpatialLinesDataFrame Object to an 'igraph'-Class Object

Description

A function to read a spatial network from a “SpatialLines” or “SpatialLinesDataFrame” object, and resolve it into a “nodelist” and “edgelist” for the following conversion.

Usage

readshpnw(ntdata, ELComputed=FALSE, longlat=FALSE, Detailed=FALSE, ea.prop=NULL)

Arguments

ntdata	A “SpatialLinesDataFrame” or “SpatialLines” object
ELComputed	If TRUE, the length of each edge will be calculated and returned
longlat	If TRUE, distances on an ellipse with WGS84 parameters will be returned
Detailed	If TRUE, all the vertices within the polylines of a spatial network will be recognised as nodes; if FALSE, only two endpoints of each polyline are treated as nodes
ea.prop	A vector (of the length equalling to the number of edge attributes in in the network “ntdata”) with values of 1 or 0: 1: the corresponding column in the data frame will be kept for the new network; 0: the corresponding column in the data frame will not be kept.

Details

This function plays the first step to convert a spatial network (in a “SpatialLines” or “SpatialLinesDataFrame” object) into an “igraph” object by returning a “nodelist” and “edgelist”.

Value

A list consisted of:

Detailed	TRUE if the output is under a “Detailed” mode;
nodelist	A “nodelist” object
edgelist	An “edgelist” object
Edgelength	If “ELComputed” is TRUE, lengths of all the edges will be returned as a numeric vector; otherwise it will be NULL.
Eadf	A data frame of attributes of the returned edges, of which the structure is a data frame with [EdgeID,(attributes inherited from the input network data)]
nodexlist	A vector contains X-coordinates of all the nodes
nodeylist	A vector contains Y-coordinates of all the nodes

Author(s)

Binbin Lu [e-mail]

Examples

data(ORN)
rtNEL<-readshpnw(ORN.nt)
nl<-rtNEL[[2]]
el<-rtNEL[[3]]
#Compute edge length
rtNEL<-readshpnw(ORN.nt, ELComputed=TRUE)
edgelength<-rtNEL[[4]]
eadf<-rtNEL[[5]]

Example output

Loading required package: igraph

Attaching package: 'igraph'

The following objects are masked from 'package:stats':

    decompose, spectrum

The following object is masked from 'package:base':

    union

shp2graph documentation built on May 1, 2019, 9:45 p.m.