# dijkstra.sp

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##### Dijkstra's shortest paths using boost C++

dijkstra's shortest paths

Keywords
graphs
##### 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.
##### 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.

##### 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.

##### 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

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

• dijkstra.sp
##### 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])

Documentation reproduced from package RBGL, version 1.48.1, License: Artistic-2.0

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