NAME
Data::Graph::Util - Utilities related to graph data structure
VERSION
This document describes version 0.007 of Data::Graph::Util (from Perl
distribution Data-Graph-Util), released on 2023-12-20.
SYNOPSIS
use Data::Graph::Util qw(
toposort
is_cyclic
is_acyclic
connected_components
);
# return nodes of a 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 nodes specified in 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
# return connected subgraphs, sorted by the largest
my @subgraphs = connected_components(
{ a=>["b"], b=>["c", "d"], d=>["c"] },
); # => return 1 element, all nodes are connected as a single graph
# return connected subgraphs, sorted by the largest
my @subgraphs = connected_components(
{ a=>["b"], b=>["c", "d"], d=>["c"],
e=>["f"],
g=>["h", "i"], j=>["a"],
},
); # => return 3 elements, there are 3 separate subgraphs
# ({a=>["b"], b=>["c", "d"], d=>["c"], j=>["a"]}, {e=>["f"]}, {g=>["h","i"]})
DESCRIPTION
Early release. More functions will be added later.
This module provides some functions related to the graph data structure.
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".
connected_components
Usage:
connected_components(\%graph) => list of subgraphs
Return list of subgraphs that are not connected to one another, sorted
by descending size. If all the nodes are connected, will return a single
subgraph (the original graph itself).
HOMEPAGE
Please visit the project's homepage at
.
SOURCE
Source repository is at
.
SEE ALSO
Articles
Related modules
Graph contains more graph-related algorithms.
Topological sort
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
CONTRIBUTOR
Jose Luis MartÃnez Torres
CONTRIBUTING
To contribute, you can send patches by email/via RT, or send pull
requests on GitHub.
Most of the time, you don't need to build the distribution yourself. You
can simply modify the code, then test via:
% prove -l
If you want to build the distribution (e.g. to try to install it locally
on your system), you can install Dist::Zilla,
Dist::Zilla::PluginBundle::Author::PERLANCAR,
Pod::Weaver::PluginBundle::Author::PERLANCAR, and sometimes one or two
other Dist::Zilla- and/or Pod::Weaver plugins. Any additional steps
required beyond that are considered a bug and can be reported to me.
COPYRIGHT AND LICENSE
This software is copyright (c) 2023, 2019, 2017, 2016 by perlancar
.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
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.