Andy Armstrong > Set-IntSpan-Fast-1.15 > Set::IntSpan::Fast

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Module Version: 1.15   Source  

NAME ^

Set::IntSpan::Fast - Fast handling of sets containing integer spans.

VERSION ^

This document describes Set::IntSpan::Fast version 1.15

SYNOPSIS ^

    use Set::IntSpan::Fast;
    
    my $set = Set::IntSpan::Fast->new();
    $set->add(1, 3, 5, 7, 9);
    $set->add_range(100, 1_000_000);
    print $set->as_string(), "\n";    # prints 1,3,5,7,9,100-1000000

DESCRIPTION ^

Set::IntSpan::Fast represents sets of integers. It is optimised for sets that contain contiguous runs of values.

    1-1000, 2000-10000      # Efficiently handled

Sets that don't have this characteristic may still be represented but some of the performance and storage space advantages will be lost. Consider using bit vectors if your set does not typically contain clusters of values.

Sets may be infinite - assuming you're prepared to accept that infinity is actually no more than a fairly large integer. Specifically the constants Set::IntSpan::Fast::NEGATIVE_INFINITY and Set::IntSpan::Fast::POSITIVE_INFINITY are defined to be -(2^31-1) and (2^31-2) respectively. To create an infinite set invert an empty one:

    my $inf = Set::IntSpan::Fast->new()->complement();

Sets need only be bounded in one direction - for example this is the set of all positive integers (assuming you accept the slightly feeble definition of infinity we're using):

    my $pos_int = Set::IntSpan::Fast->new();
    $pos_int->add_range(1, $pos_int->POSITIVE_INFINITY);

Set representation

The internal representation used is extremely simple: a set is represented as a list of integers. Integers in even numbered positions (0, 2, 4 etc) represent the start of a run of numbers while those in odd numbered positions represent the ends of runs. As an example the set (1, 3-7, 9, 11, 12) would be represented internally as (1, 2, 3, 8, 11, 13).

Comparision with Set::IntSpan

The Set::IntSpan module represents sets of integers as a number of inclusive ranges, for example '1-10,19-23,45-48'. Because many of its operations involve linear searches of the list of ranges its overall performance tends to be proportional to the number of distinct ranges. This is fine for small sets but suffers compared to other possible set representations (bit vectors, hash keys) when the number of ranges grows large.

This module also represents sets as ranges of values but stores those ranges in order and uses a binary search for many internal operations so that overall performance tends towards O log N where N is the number of ranges.

Set::IntSpan::Fast::XS

If Set::IntSpan::Fast::XS is installed it will automatically be used when a new Set::IntSpan::Fast is created. There is no need to change any code; the XS module is automatically detected and loaded.

If you have a C compiler consider installing Set::IntSpan::Fast::XS for even better performance.

INTERFACE ^

new

Create a new set. Any arguments will be processed by a call to add_from_string:

    my $set = Set::IntSpan::Fast->new( '1, 3, 5, 10-100' );

Because add_from_string handles multiple arguments this will work:

    my @nums = ( 1, 2, 3, 4, 5 );
    my $set = Set::IntSpan::Fast->new( @nums );

Bear in mind though that this validates each element of the array is it would if you called add_from_string so for large sets it will be slightly more efficient to create an empty set and then call add.

invert

Complement the set. Because our notion of infinity is actually disappointingly finite inverting a finite set results in another finite set. For example inverting the empty set makes it contain all the integers between NEGATIVE_INFINITY and POSITIVE_INFINITY inclusive.

As noted above NEGATIVE_INFINITY and POSITIVE_INFINITY are actually just big integers.

copy

Return an identical copy of the set.

    my $new_set = $set->copy();

add( $number ... )

Add the specified integers to the set. Any number of arguments may be specified in any order. All arguments must be integers between Set::IntSpan::NEGATIVE_INFINITY and Set::IntSpan::POSITIVE_INFINITY inclusive.

remove( $number ... )

Remove the specified integers from the set. It is not an error to remove non-members. Any number of arguments may be specified.

add_range( $from, $to )

Add the inclusive range of integers to the set. Multiple ranges may be specified:

    $set->add_range(1, 10, 20, 22, 15, 17);

Each pair of arguments constitute a range. The second argument in each pair must be greater than or equal to the first.

add_from_string( $string )

Add items to a set from a string representation, of the same form as as_string. Multiple strings may be supplied:

    $set->add_from_string( '1-10, 30-40', '100-200' );

is equivalent to

    $set->add_from_string( '1-10, 30-40, 100-200' );

By default items are separated by ',' and ranges delimited by '-'. You may select different punctuation like this:

    $set->add_from_string( 
        { sep => ';', range => ':' },
        '1;3;5;7:11;19:27'
    );

When supplying an options hash in this way the sep and range option may be either a regular expression or a literal string.

    $set->add_from_string( 
        { sep => qr/:+/, range => qr/[.]+/ },
        '1::3::5:7...11:19..27'
    );

Any embedded whitespace in the string will be ignored.

remove_range( $from, $to )

Remove the inclusive range of integers from the set. Multiple ranges may be specified:

    $set->remove_range(1, 10, 20, 22, 15, 17);

Each pair of arguments constitute a range. The second argument in each pair must be greater than or equal to the first.

remove_from_string( $string )

Remove items to a set from a string representation, of the same form as as_string. As with add_from_string the punctuation characters may be specified.

merge( $set ... )

Merge the members of the supplied sets into this set. Any number of sets may be supplied as arguments.

empty

Empty a set.

Operators

complement

Returns a new set that is the complement of this set. See the comments about our definition of infinity above.

union( $set ... )

Return a new set that is the union of this set and all of the supplied sets.

    $un = $set->union( $other_set );

intersection( $set )

Return a new set that is the intersection of this set and all the supplied sets.

    $in = $set->intersection( $other_set );

xor( $set )

Return a new set that contains all of the members that are in this set or the supplied set but not both. Can actually handle more than two sets in which case it returns a set that contains all the members that are in some of the sets but not all of the sets.

diff( $set )

Return a set containing all the elements that are in this set but not the supplied set.

Tests

is_empty

Return true if the set is empty.

contains( $number )

Return true if the specified number is contained in the set.

contains_any($number, $number, $number ...)

Return true if the set contains any of the specified numbers.

contains_all($number, $number, $number ...)

Return true if the set contains all of the specified numbers.

contains_all_range( $low, $high )

Return true if all the numbers in the range $low to $high (inclusive) are in the set.

cardinality( [ $clip_lo, $clip_hi ] )

Returns the number of members in the set. If a clipping range is supplied return the count of members that fall within that inclusive range.

superset( $set )

Returns true if this set is a superset of the supplied set. A set is always a superset of itself, or in other words

    $set->superset( $set )

returns true.

subset( $set )

Returns true if this set is a subset of the supplied set. A set is always a subset of itself, or in other words

    $set->subset( $set )

returns true.

equals( $set )

Returns true if this set is identical to the supplied set.

Getting set contents

as_array

Return an array containing all the members of the set in ascending order.

as_string

Return a string representation of the set.

    my $set = Set::IntSpan::Fast->new();
    $set->add(1, 3, 5, 7, 9);
    $set->add_range(100, 1_000_000);
    print $set->as_string(), "\n";    # prints 1,3,5,7,9,100-1000000

You may optionally supply a hash containing sep and range options:

    print $set->as_string({ sep => ';', range => '*' ), "\n";
        # prints 1;3;5;7;9;100*1000000

iterate_runs( [ $clip_lo, $clip_hi ] )

Returns an iterator that returns each run of integers in the set in ascending order. To iterate all the members of the set do something like this:

    my $iter = $set->iterate_runs();
    while (my ( $from, $to ) = $iter->()) {
        for my $member ($from .. $to) {
            print "$member\n";
        }
    }

If a clipping range is specified only those members that fall within the range will be returned.

Constants

The constants NEGATIVE_INFINITY and POSITIVE_INFINITY are exposed. As noted above these are infinitely smaller than infinity but they're the best we've got. They're not exported into the caller's namespace so if you want to use them you'll have to use their fully qualified names:

    $set->add_range(1, Set::IntSpan::Fast::POSITIVE_INFINITY);

DIAGNOSTICS ^

Range list must have an even number of elements

The lists of ranges passed to add_range and remove_range consist of a number of pairs of integers each of which specify the start and end of a range.

Range limits must be integers

You may only add integers to sets.

Range limits must be in ascending order

When specifying a range in a call to add_range or remove_range the range bounds must be in ascending order. Multiple ranges don't need to be in any particular order.

Value out of range

Sets may only contain values in the range NEGATIVE_INFINITY to POSITIVE_INFINITY inclusive.

That's very kind of you - but I expect you meant complement()

The method that complements a set is called complement.

I need two sets to compare

superset and subset need two sets to compare. They may be called either as a function:

    $ss = Set::IntSpan::Fast::subset( $s1, $s2 )

or as a method:

    $ss = $s1->subset( $s2 );

Invalid Range String

The range string must only contain a comma separated list of ranges, with a hyphen used as the range limit separator. e.g. "1,5,8-12,15-29".

CONFIGURATION AND ENVIRONMENT ^

Set::IntSpan::Fast requires no configuration files or environment variables.

DEPENDENCIES ^

    Data::Types
    List::Util

INCOMPATIBILITIES ^

Although this module was conceived as a replacement for Set::IntSpan it isn't a drop-in replacement.

BUGS AND LIMITATIONS ^

No bugs have been reported.

Please report any bugs or feature requests to bug-set-intspan-fast@rt.cpan.org, or through the web interface at http://rt.cpan.org.

AUTHOR ^

Andy Armstrong <andy@hexten.net>

CREDITS ^

K. J. Cheetham http://www.shadowcatsystems.co.uk/ for add_from_string, remove_from_string. I butchered his code so any errors are mine.

LICENCE AND COPYRIGHT ^

Copyright (c) 2006-2008, Andy Armstrong <andy@hexten.net>. All rights reserved.

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See perlartistic.

DISCLAIMER OF WARRANTY ^

BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

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