/usr/share/perl5/Math/SparseVector.pm is in libmath-sparsevector-perl 0.04-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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use 5.006;
use strict;
use warnings;
require Exporter;
our @ISA = qw(Exporter);
# Items to export into callers namespace by default. Note: do not export
# names by default without a very good reason. Use EXPORT_OK instead.
# Do not simply export all your public functions/methods/constants.
# This allows declaration use Math::SparseVector ':all';
# If you do not need this, moving things directly into @EXPORT or @EXPORT_OK
# will save memory.
our %EXPORT_TAGS = ( 'all' => [ qw(
) ] );
our @EXPORT_OK = ( @{ $EXPORT_TAGS{'all'} } );
our @EXPORT = qw(
);
our $VERSION = '0.04';
use overload
'++' => 'incr',
'+' => 'add',
'fallback' => undef;
# sparse vector contructor
# creates an empty sparse vector
sub new
{
my $class = shift;
my $self = {};
bless($self,$class);
return $self;
}
# sets value at given index
sub set
{
my $self = shift;
my $key = shift;
my $value = shift;
if(!defined $key || !defined $value)
{
print STDERR "Usage: vector->set(key,value)\n";
exit;
}
if($value==0)
{
print STDERR "Can not store 0 in the Math::SparseVector.\n";
exit;
}
$self->{$key} = $value;
}
# returns value at given index
sub get
{
my $self = shift;
my $key = shift;
if(!defined $key)
{
print STDERR "Usage: vector->get(key)\n";
exit;
}
if(defined $self->{$key})
{
return $self->{$key};
}
return 0;
}
# returns indices of non-zero values in sorted order
sub keys
{
my $self = shift;
my @indices = keys %{$self};
my @sorted = sort {$a <=> $b} @indices;
return @sorted;
}
# returns 1 if the vector is empty
sub isnull
{
my $self = shift;
my @indices = $self->keys;
if(scalar(@indices)==0)
{
return 1;
}
return 0;
}
# prints sparse vector
sub print
{
my $self = shift;
foreach my $ind ($self->keys)
{
print "$ind " . $self->get($ind) . " ";
}
print "\n";
}
# returns the equivalent string form
sub stringify
{
my $self = shift;
my $str="";
foreach my $ind ($self->keys)
{
$str.= "$ind " . $self->get($ind) . " ";
}
chop $str;
return $str;
}
# increments value at given index
sub incr
{
my $self = shift;
my $key = shift;
if(!defined $key)
{
print STDERR "Usage: vector->incr(key)\n";
exit;
}
$self->{$key}++;
}
# adds 2 sparse vectors
sub add
{
my $self = shift;
my $v2 = shift;
if(!defined $v2)
{
print STDERR "Usage: v1->add(v2)\n";
exit;
}
foreach my $key ($v2->keys)
{
if(defined $self->{$key})
{
$self->{$key}+=$v2->get($key);
}
else
{
$self->{$key}=$v2->get($key);
}
}
}
# returns the norm
sub norm
{
my $self = shift;
my $sum = 0;
foreach my $key ($self->keys)
{
my $value = $self->{$key};
$sum += $value ** 2;
}
return sqrt $sum;
}
# normalizes given sparse vector
sub normalize
{
my $self = shift;
my $vnorm = $self->norm;
if($vnorm != 0)
{
$self->div($vnorm);
}
}
sub dot
{
my $self = shift;
my $v2 = shift;
if(!defined $v2)
{
print STDERR "Usage: v1->dot(v2)\n";
exit;
}
my $dotprod = 0;
# optimize to do lesser comparisons by looping on
# the smaller vector
if (scalar($v2->keys) < scalar($self->keys)) {
# v2 is smaller
foreach my $key ($v2->keys)
{
if(defined $self->{$key})
{
$dotprod += $v2->get($key) * $self->{$key};
}
}
} else {
# self is smaller or equal to v2
foreach my $key ($self->keys)
{
if(defined $v2->{$key})
{
$dotprod += $v2->get($key) * $self->{$key};
}
}
}
return $dotprod;
}
# divides each vector entry by a given divisor
sub div
{
my $self = shift;
my $divisor = shift;
if(!defined $divisor)
{
print STDERR "Usage: v1->div(DIVISOR)\n";
exit;
}
if($divisor==0)
{
print STDERR "Divisor 0 not allowed in Math::SparseVector::div().\n";
exit;
}
foreach my $key ($self->keys)
{
$self->{$key}/=$divisor;
}
}
# adds a given sparse vector to a binary sparse vector
sub binadd
{
my $v1 = shift;
my $v2 = shift;
if(!defined $v2)
{
print STDERR "Usage: v1->binadd(v2)\n";
exit;
}
foreach my $key ($v2->keys)
{
$v1->{$key}=1;
}
}
# deallocates all the vector entries
sub free
{
my $self = shift;
%{$self}=();
undef %{$self};
}
1;
__END__
=head1 NAME
Math::SparseVector - Supports sparse vector operations such as
setting a value in a vector, reading a value at a given index,
obtaining all indices, addition and dot product of two sparse vectors,
and vector normalization.
=head1 MODULE HISTORY
This module is the successor to Sparse::Vector, which was re-cast
into this new namespace in order to introduce another module
Math::SparseMatrix, which makes use of this module.
=head1 SYNOPSIS
use Math::SparseVector;
# creating an empty sparse vector object
$spvec=Math::SparseVector->new;
# sets the value at index 12 to 5
$spvec->set(12,5);
# returns value at index 12
$value = $spvec->get(12);
# returns the indices of non-zero values in sorted order
@indices = $spvec->keys;
# returns 1 if the vector is empty and has no keys
if($spvec->isnull) {
print "vector is null.\n";
}
else {
print "vector is not null.\n";
}
# print sparse vector to stdout
$spvec->print;
# returns the string form of sparse vector
# same as print except the string is returned
# rather than displaying on stdout
$spvec->stringify;
# adds sparse vectors v1, v2 and stores
# result into v1
$v1->add($v2);
# adds binary equivalent of v2 to v1
$v1->binadd($v2);
# binary equivalnet treats all non-zero values
# as 1s
# increments the value at index 12
$spvec->incr(12);
# divides each vector entry by a given divisor 4
$spvec->div(4);
# returns norm of the vector
$spvec_norm = $spvec->norm;
# normalizes a sparse vector
$spvec->normalize;
# returns dot product of the 2 vectors
$dotprod = $v1->dot($v2);
# deallocates all entries
$spvec->free;
=head1 USAGE NOTES
=over
=item 1. Loading Math::SparseVector Module
To use this module, you must insert the following line in your Perl program
before using any of the supported methods.
use Math::SparseVector;
=item 2. Creating a Math::SparseVector Object
The following line creates a new object of Math::SparseVector class referred
with the name 'spvec'.
$spvec=Math::SparseVector->new;
The newly created 'spvec' vector will be initially empty.
=item 3. Using Methods
Now you can use any of the following methods on this 'spvec' Math::SparseVector
object.
=over
=item 1. set(i,n) - Sets the value at index i to n
# equivalent to $spvec{12}=5;
$spvec->set(12,5);
=item 2. get(i) - Returns the value at index i
# equivalent to $value=$spvec{12};
$value = $spvec->get(12);
=item 3. keys() - Returns the indices of all non-zero values in the vector
# equivalent to @keys=sort {$a <=> $b} keys %spvec;
@indices = $spvec->keys;
=item 4. isnull() - Returns 1 if the vector is empty and has no keys
# similar to
# if(scalar(keys %spvec)==0) {print "vector is null.\n";}
if($spvec->isnull) { print "vector is null.\n"; }
=item 5. print() - Prints the sparse vector to stdout - Output will show a list of space separated 'index value' pairs for each non-zero 'value' in the vector.
# similar to
# foreach $ind (sort {$a<=>$b} keys %spvec)
# { print "$ind " . $spvec{$ind} . " "; }
$spvec->print;
=item 6. stringify() - Returns the vector in a string form. Same as print() method except the vector is written to a string that is returned instead of displaying onto stdout
# the below will do exactly same as $spvec->print;
$string=$spvec->stringify;
print "$string\n";
=item 7. v1->add(v2) - Adds contents of v2 to vector v1.
Similar to v1+=v2
$v1->add($v2);
If v1 = (2, , , 5, 8, , , , 1)
& v2 = ( , 1, , 3, , , 5, , 9)
where blanks show the 0 values that are not stored in
Math::SparseVector.
After $v1->add($v2);
v1 = (2, 1, , 8, 8, , 5, , 10) and v2 remains same
=item 8. v1->binadd(v2) - Binary equivalent of v2 is added into v1. Binary equivalent of a vector is obtained by setting all non-zero values to 1s.
If v1 = (1, , , 1, 1, , , , 1)
& v2 = ( , 1, , 1, , , 1, , 1)
Then, after v1->binadd(v2),
v1 will be (1, 1, , 1, 1, , 1, , 1).
If v1 = (1, , , 1, 1, , , , 1)
& v2 = ( , 1, , 3, , , 5, , 9)
v1->binadd(v2);
will set v1 to (1, 1, , 1, 1, , 1, , 1).
=item 9. incr(i) - Increments the value at index i
# is similar to $spvec{12}++;
$spvec->incr(12);
=item 10. div(n) - Divides each vector entry by a given divisor n
$spvec->div(4);
If spvec = (2, , , 5, 8, , , , 1)
Then, $spvec->div(4)
will set spvec to (0.5, , , 1.25, 2, , , , 0.25)
=item 11. norm() - Returns the norm of a given vector
$spvec_norm = $spvec->norm;
If spvec = (2, , , 5, 8, , , , 1)
$spvec->norm will return the value
= sqrt(2^2 + 5^2 + 8^2 + 1)
= sqrt(4 + 25 + 64 + 1)
= 9.69536
=item 12. v1->dot(v2) - Returns the dot product of two vectors
$dotprod = $v1->dot($v2);
If v1 = (2, , , 5, 8, , , , 1)
& v2 = ( , 1, , 3, , , 5, , 9)
v1->dot(v2) returns
5*3 + 1*9 = 15 + 9 = 24
=item 13. free() - Deallocates all entries and makes the vector empty
$spvec->free;
will set spvec to null vector ()
=back
=back
=head1 AUTHORS
Amruta Purandare, University of Pittsburgh
amruta at cs.pitt.edu
Ted Pedersen, University of Minnesota, Duluth
tpederse at d.umn.edu
Mahesh Joshi, Carnegie-Mellon University
maheshj at cmu.edu
=head1 COPYRIGHT AND LICENSE
Copyright (c) 2006-2008, Amruta Purandare, Ted Pedersen, Mahesh Joshi
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
this program; if not, write to
The Free Software Foundation, Inc.,
59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
=cut
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