NAME
Data::Graph::Util - Utilities related to graph data structure
VERSION
This document describes version 0.006 of Data::Graph::Util (from Perl
distribution Data-Graph-Util), released on 2019-02-15.
SYNOPSIS
use Data::Graph::Util qw(toposort is_cyclic is_acyclic);
# return nodes that satisfy the following graph: a must come before b, b must
# come before c & d, and d must come before c.
my @sorted = toposort(
{ a=>["b"], b=>["c", "d"], d=>["c"] },
); # => ("a", "b", "d", "c")
# sort specified nodes (2nd argument) using the graph. nodes not mentioned in
# the graph will be put at the end. duplicates are not removed.
my @sorted = toposort(
{ a=>["b"], b=>["c", "d"], d=>["c"] },
["e", "a", "b", "a"]
); # => ("a", "a", "b", "e")
# check if a graph is cyclic
say is_cyclic ({a=>["b"]}); # => 0
say is_acyclic({a=>["b"]}); # => 1
# check if a graph is acyclic (not cyclic)
say is_cyclic ({a=>["b"], b=>["c"], c=>["a"]}); # => 1
say is_acyclic({a=>["b"], b=>["c"], c=>["a"]}); # => 0
DESCRIPTION
Early release. More functions will be added later.
Keywords: topological ordering, dependency sorting, dependency ordering.
FUNCTIONS
None are exported by default, but they are exportable.
toposort
Usage:
toposort(\%graph[ , \@nodes ]) => sorted list
Perform a topological sort on graph (currently using the Kahn
algorithm). Will return the nodes of the graph sorted topologically.
Will die if graph cannot be sorted, e.g. when graph is cyclic.
If "\@nodes" is specified, will instead return @nodes sorted according
to the topological order. Duplicates are allowed and not removed. Nodes
not mentioned in graph are also allowed and will be put at the end.
is_cyclic
Usage:
is_cyclic(\%graph) => bool
Return true if graph contains at least one cycle. Currently implemented
by attempting a topological sort on the graph. If it can't be performed,
this means the graph contains cycle(s).
is_acyclic
Usage:
is_acyclic(\%graph) => bool
Return true if graph is acyclic, i.e. contains no cycles. The opposite
of "is_cyclic".
HOMEPAGE
Please visit the project's homepage at
.
SOURCE
Source repository is at
.
BUGS
Please report any bugs or feature requests on the bugtracker website
When submitting a bug or request, please include a test-file or a patch
to an existing test-file that illustrates the bug or desired feature.
SEE ALSO
Algorithm::Dependency can also do topological sorting, but it is more
finicky with input: graph cannot be epmty and all nodes need to be
specified.
Sort::Topological can also sort a DAG, but cannot handle cyclical graph.
It also performs poorly and eats too much RAM on larger graphs.
See Bencher::Scenario::GraphTopologicalSortModules for benchmarks.
AUTHOR
perlancar
COPYRIGHT AND LICENSE
This software is copyright (c) 2019, 2017, 2016 by perlancar@cpan.org.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.