points2network: Integrate a point data set with a network

Description

In order to associate a point data set with a given network, this function finds a corresponding node for each point in the data set under a certain rule(see details).

Usage

points2network(ntdata,pointsxy,mapping.method=1,ELComputed=FALSE,longlat=F,
               Detailed=F, ea.prop=NULL)

Arguments

ntdata

a “SpatialLinesDataFrame” object

pointsxy

A two column matrix contains X-Y coordinates of the points.

mapping.method

Mapping methods between the given points and network will be used, see the details below

ELComputed

if TRUE, the edge length will be computed

longlat

if TRUE, use distances on an ellipse with WGS84 parameters

Detailed

if TRUE, all the points of polylines will be regarded as nodes in the network; if FALSE, only endpoints of polylines are treated as nodes

ea.prop

A vector contains 1 or 0 values (the length equals to the number of arributes of the “ntdata”):

1: the corresponding attribute will be kept and re-orgnised for the new network;

0: the corresponding attribute will not be kept.

Value

A list consisted of:

nodelist

A “nodelist” object

edgelist

An “edgelist” object

CoorespondIDs

A vector contains cooresponding node IDs for each point

nodexlist

A vector contains X-coordinates of all the nodes

nodeylist

A vector contains Y-coordinates of all the nodes

Eadf

a data frame of edge attributes, dataframe(EdgeID,... (attributes extracted from original file)...)

VElist

A list of virtual edges if existed

Edgelength

If ELComputed is TRUE, Edgelength will be a vector consisted of edge lengths cooresponding to each edge, else it will be NULL

Details

The value of mapping.method can be 1,2,3 or 4, which respectively means:

1: Mapping each point to the nearest node in the network/graph

2: Mapping each point to the nearest point (add them as nodes if they are not) on the network

3: Add a new edge(virtual edge) between each point and the nearest node

4: Add a new edge(virtual edge) between each point and the nearest point

Examples

Run this code

# NOT RUN {
data(ORN)
pts<-spsample(rn, 100, type="random")
ptsxy<-coordinates(pts)[,1:2]
ptsxy<-cbind(ptsxy[,1]+0.008,ptsxy[,2]+0.008)
#Mapping each point to the nearest node in the network/graph
res<-points2network(ntdata=rn,pointsxy=ptsxy, mapping.method=1)
ptsinnt.view(ntdata=rn, nodelist=res[[1]], pointsxy=ptsxy,
             CoorespondIDs=res[[3]])
#Mapping each point to the nearest point (add them as nodes if they are not) on 
#the network
res<-points2network(ntdata=rn,pointsxy=ptsxy, mapping.method=2,ea.prop=rep(0,37))
ptsinnt.view(ntdata=rn, nodelist=res[[1]], pointsxy=ptsxy, CoorespondIDs=res[[3]]) 
#Add a new edge(Virtual edge) between each point and the nearest node
res<-points2network(ntdata=rn,pointsxy=ptsxy, mapping.method=3,ea.prop=rep(0,37))
VElist<-res[[7]]
ptsinnt.view(ntdata=rn, nodelist=res[[1]], pointsxy=ptsxy, CoorespondIDs=res[[3]], 
             VElist=VElist)
#Add a new edge(Virtual edge) between each point and the nearest point
res<-points2network(ntdata=rn,pointsxy=ptsxy, mapping.method=4,ea.prop=rep(0,37))
VElist<-res[[7]]
ptsinnt.view(ntdata=rn, nodelist=res[[1]], pointsxy=ptsxy, CoorespondIDs=res[[3]],
             VElist=VElist) 
# }