NAME

Graph::BitMatrix - create and manipulate a V x V bit matrix of graph G

SYNOPSIS

use Graph::BitMatrix;
use Graph::Directed;
my $g  = Graph::Directed->new;
$g->add_...(); # build $g
my $m = Graph::BitMatrix->new($g, %opt);
$m->get($u, $v)
$m->set($u, $v)
$m->unset($u, $v)
$m->get_row($u, $v1, $v2, ..., $vn)
$m->set_row($u, $v1, $v2, ..., $vn)
$m->unset_row($u, $v1, $v2, ..., $vn)
$a->vertices()

DESCRIPTION

This class enables creating bit matrices that compactly describe the connected of the graphs.

Class Methods

new($g)

Create a bit matrix from a Graph $g. The %opt, if present, can have the following options:

• connect_edges

  If true or if not present, set the bits in the bit matrix that correspond to edges. If false, do not set any bits. In either case the bit matrix of V x V bits is allocated.

• transpose

  If true, set the bits in the bit matrix that correspond to edges but in the reverse direction. This has the effect of transposing the matrix. Obviously makes no difference to the result for undirected graphs.

Object Methods

get($u, $v)

Return true if the bit matrix has a "one bit" between the vertices $u and $v; in other words, if there is (at least one) a vertex going from $u to $v. If there is no vertex and therefore a "zero bit", return false.

set($u, $v)

Set the bit between the vertices $u and $v; in other words, connect the vertices $u and $v by an edge. The change does not get mirrored back to the original graph. Returns nothing.

unset($u, $v)

Unset the bit between the vertices $u and $v; in other words, disconnect the vertices $u and $v by an edge. The change does not get mirrored back to the original graph. Returns nothing.

get_row($u, $v1, $v2, ..., $vn)

Test the row at vertex u for the vertices v1, v2, ..., vn Returns a list of n truth values.

set_row($u, $v1, $v2, ..., $vn)

Sets the row at vertex u for the vertices v1, v2, ..., vn, in other words, connects the vertex u to the vertices vi. The changes do not get mirrored back to the original graph. Returns nothing.

unset_row($u, $v1, $v2, ..., $vn)

Unsets the row at vertex u for the vertices v1, v2, ..., vn, in other words, disconnects the vertex u from the vertices vi. The changes do not get mirrored back to the original graph. Returns nothing.

vertices

Return the list of vertices in the bit matrix.

ALGORITHM

The algorithm used to create the matrix is two nested loops, which is O(V**2) in time, and the returned matrices are O(V**2) in space.

AUTHOR AND COPYRIGHT

Jarkko Hietaniemi jhi@iki.fi

LICENSE

This module is licensed under the same terms as Perl itself.