NAME

Statistics::SparseVector - Perl5 extension for representing and manipulating sparse binary and integer vectors

SYNOPSIS

use Statistics::SparseVector;

# methods that create new bitvectors
$vec = Statistics::SparseVector->new($n);
$vec2 = $vec1->Clone();
$vec = Statistics::SparseVector->new_Enum($n, $s);
$vec = Statistics::SparseVector->new_Bin($n, $s);
$vec = Statistics::SparseVector->new_Int($n, $s);

# miscellaneous
$vec2->Substitute_Vector($vec1, $of22, $len2, $off1, $len1);
$vec->insert_column($pos, $val);
$vec->delete_column($pos);
$vec->Size();
$vec->to_Enum();
$vec->to_Bin($sep);
$vec->Fill();
$vec->Empty();
$vec->increment();
$n = $vec->Norm();
@list = $vec->indices();

# manipulation on the bit level
$vec->Bit_Off($i);
$vec->Bit_On($i);
$vec->Inc($i);
$vec->bit_flip($i);
$vec->bit_test($i);

# overloaded operators
# increment
$vec++;
# stringify
"$vec"

DESCRIPTION

This module implements sparse bitvectors. Several methods for manipulating bitvectors are implemented.

Creation of bitvectors

new

$vec = Statistics::BitVector->new($n);

A bitvector of length $n is created. All bits are zero.

Clone

$clone = $vec->Clone();

A copy of $vec is returned.

new_Enum

$vec = Statistics::BitVector->new_Enum($enumstring, $n);

A new vector of length $n is created from the comma-separated list of in $enumstring.

new_Bin

$vec = Statistics::BitVector->new_Bin($n, $string);

A new vector of length $n is created from bitstring $string.

new_Int

$vec = Statistics::BitVector->new_Int($n, $intlist);

A new vector of length $n is created from whitespace-separated list of integers $intlist.

Vector-wide manipulation of vector elements

Substitute_Vector

$vec2->Substitute_Vector($vec1, $off2, $len2, $off1, $len1);

$len2 contiguous bits in target vector $vec2 starting from $off2 are replaced by $len1 contiguous bits from source vector $vec1 starting at bit $off1. If $off2 equals the length of $vec2 the bits from $vec1 are appended. If $len1 is zero the $len2 bits from $vec2 are deleted.

delete_column

$vec->delete_column($i);

Delete position $i, the other elements are shifted as necessary.

insert_column

$vec->insert_column($i, $val);

Insert a vector element at position $i with value $val.

Fill

$vec->Fill();

All bits of $vec are set to one.

Empty

$vec->Empty();

All bits of $vec are set to zero.

increment

$vec->increment(); $vec++;

The integer value of the bitvector is increased by one.

Bit_Off

$vec->Bit_Off($i);

Bit $i is set to zero.

Bit_On

$vec->Bit_On($i);

Bit $i is set to one.

Inc

$vec->Inc($i);

The integer at position $i is increased by one.

bit_flip

$vec->bit_flip($i);

Bit $i is flipped.

bit_test

$vec->bit_test($i);

Returns 1 if bit $i is one, 0 otherwise.

Miscellany

Size

$n = $vec->Size();

Returns the size of the vector.

to_Enum

$enumstring = $vec->to_Enum();

Returns a comma-separated list of bits that are set.

indices

Returns an array of indices of bits that are set.

to_Bin

$bitstring = $vec->to_Bin($sep);

Returns a string of bits separated by $sep; bits should be read from left to right

Norm

Returns the number of set bits.

Overloaded operators

++

$vec++;

Same as method increment.

Double quotes

$string = "$vec";

Data::Dumper wants to stringify vectors. Probably because Statistics::SparseVector is an overloaded package it expects double quotes to be overloaded as well.

REMARKS ABOUT THE IMPLEMENTATION

• Internally sparse vectors are represented by hashes.

• Only a few methods from Bit::Vector are implemented. Maybe new ones will follow in the future.

• Method Substitute_Vector is not thorougly debugged.

VERSION

Version 0.2.

AUTHOR

SEE ALSO

perl(1), Statistics::MaxEntropy(3), Statistics::ME.wrapper.pl(3), Statistics::Candidates(3).

COPYRIGHT

Statistics::MaxEntropy comes with ABSOLUTELY NO WARRANTY and may be copied only under the terms of the GNU Library General Public License (version 2, or later), which may be found in the distribution.