| Directed {shp2graph} | R Documentation |
Orientate all the edges in a given edgelist
Description
A function to orientate each edge according to the given vector.
Usage
Directed(edgelist, direction.v=rep(0,length(edgelist[,1])), eadf=NULL)
Arguments
edgelist |
An “edgelist” object |
direction.v |
A vector (of the length equalling to the number of edges in the given “edgelist”) with values of 1 (TRUE) or 0 (FALSE), 1 (TRUE) indicates a directed (one-way) edge, while 0 (FALSE) means an undirected (double-way) edge |
eadf |
A data frame of attributes corresponding to all the edges; |
Details
Within a road network, some road segments might be one-way while the rest are double-way. This suitation makes it complex to define directed or undirected edges in a graph. This function is to orientate each edge according to the given vector, “direction.v”: 1 (TRUE) indicates one-way, while 0 (FALSE) represents double-way. All the double-way (undirected) edges in the given “edgelist” are redefined as two directed edges (e.g. a double-way (undirected) edge(nid1, nid2) is redefined as two one-way (directed) edges, (nid1, nid2) and (nid2, nid1)). The one-way (directed) edges are left in their directed forms. In other words, all the edges returned by this function will be directed, and used to be construct a directed graph.
Value
A list consisted of:
newEdgelist |
An “edgelist” object with directed edges |
newEadf |
A data frame of attributes for the new “edgelist” |
Author(s)
Binbin Lu binbinlu@whu.edu.cn