NAME
dijkstra - single-source distance filter
SYNOPSIS
dijkstra [ -ap? ] [ sourcenode file ]
DESCRIPTION
dijkstra reads a stream of graphs and for each computes the distance of
every node from sourcenode. Edge length is given in the len attribute,
and the default is 1. The dist attribute of every node is set to its
distance from sourcenode. If the -p flag is used, the prev attribute
of each node reachable from sourcenode is set to the name of the
previous node on a shortest path. The graph attribute maxdist is set
to the maximum dist of all nodes in the graph.
By default, if the graph is disconnected, the dist attribute of nodes
unreachable from sourcenode are left untouched, and maxdist is set to
the maximum of any previous value and the largest distance recorded in
this run. On the other hand, if the -a flag is used, the dist attribute
of an unreachable node is assigned a very large value, and maxdist
records the maximum distance found in the component containing
sourcenode.
Any number of sourcenode file pairs may be given. If the last file is
missing, stdin is used. All output is written to stdout.
In a typical application, dist and maxdist can drive a downstream
calculation of color or some other attribute.
SEE ALSO
gvpr(1), gvcolor(1), libgraph(3)
21 March 2001