dijkstra.sp {RBGL} | R Documentation

## 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.

### 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`.

### Author(s)

VJ Carey <stvjc@channing.harvard.edu>

### 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])

[Package RBGL version 1.58.2 Index]