RBGL (version 1.48.1)

dijkstra.sp: Dijkstra's shortest paths using boost C++

Description

dijkstra's shortest paths

Usage

dijkstra.sp(g,start=nodes(g)[1], eW=unlist(edgeWeights(g)))

Arguments

g

instance of class graph

start

character: node name for start of path

eW

numeric: edge weights.

Value

A list with elements:

distance

The vector of distances from start to each node of g; includes Inf when there is no path from start.

penult

A vector of indices (in nodes(g)) of predecessors corresponding to each node on the path from that node back to start

. For example, if the element one of this vector has value 10, that means that the predecessor of node 1 is node 10. The next predecessor is found by examining penult[10].

start

The start node that was supplied in the call to dijkstra.sp.

Details

These functions are interfaces to the Boost graph library C++ routines for Dijkstra's shortest paths.

For some graph subclasses, computing the edge weights can be expensive. If you are calling dijkstra.sp in a loop, you can pass the edge weights explicitly to avoid the edge weight creation cost.

References

Boost Graph Library ( www.boost.org/libs/graph/doc/index.html )

The Boost Graph Library: User Guide and Reference Manual; by Jeremy G. Siek, Lie-Quan Lee, and Andrew Lumsdaine; (Addison-Wesley, Pearson Education Inc., 2002), xxiv+321pp. ISBN 0-201-72914-8

See Also

bellman.ford.sp, dag.sp, johnson.all.pairs.sp, sp.between

Examples

con1 <- file(system.file("XML/dijkex.gxl",package="RBGL"), open="r")
dd <- fromGXL(con1)
close(con1)
dijkstra.sp(dd)
dijkstra.sp(dd,nodes(dd)[2])

con2 <- file(system.file("XML/ospf.gxl",package="RBGL"), open="r")
ospf <- fromGXL(con2)
close(con2)
dijkstra.sp(ospf,nodes(ospf)[6])