NAME
Sort::XS - a ( very ) fast XS sort alternative for one dimension list
SYNOPSIS
use Sort::XS qw/xsort/;
# use it simply
my $sorted = xsort([1, 5, 3]);
$sorted = [ 1, 3, 5 ];
# personalize your xsort with some options
my $list = [ 1..1000, 200..1100 ]
my $sorted = xsort( $list )
or xsort( list => $list )
or xsort( list => $list, algorithm => 'quick' )
or xsort( $list, algorithm => 'quick', data => integer )
or xsort( list => $list, algorithm => 'heap', data => 'integer' )
or xsort( list => $list, algorithm => 'merge', data => 'string' );
# if you [ mainly ] use very small arrays ( ~ 10 rows )
# prefer using directly one of the XS subroutines
$sorted = Sort::XS::quick_sort( $list )
or Sort::XS::heap_sort($list)
or Sort::XS::merge_sort($list)
or Sort::XS::insertion_sort($list);
DESCRIPTION
This module provides several common sort algorithms implemented as XS.
Sort can only be used on one dimension list of integers or strings.
It's goal is not to replace the internal sort subroutines, but to
provide a better alternative in some specifics cases :
- no need to specify a comparison operator
- sorting a mono dimension list
ALGORITHMS
I've chosen to use quicksort as the default method ( even if it s not a
stable algorithm ), you can also consider to use heapsort which provides
a worst case in "n log n".
Chosing the correct algorithm depends on distribution of your values and
size of your list. Quicksort provides an average good solution, even if
in some case it will be better to use a different choice.
quick sort
This is the default algorithm. In pratice it provides the best results
even if in worst case heap sort will be a better choice.
read http://en.wikipedia.org/wiki/Quicksort for more informations
heap sort
A little slower in practice than quicksort but provide a better worst
case runtime.
read http://en.wikipedia.org/wiki/Heapsort for more informations
merge sort
Stable sort algorithm, that means that in any case the time to compute
the result will be similar. It's still a better choice than the internal
perl sort.
read http://en.wikipedia.org/wiki/Mergesort for more informations
insertion sort
Provide one implementation of insertion sort, but prefer using either
any of the previous algorithm or even the perl internal sort.
read http://en.wikipedia.org/wiki/Mergesort for more informations
perl
this is not an algorithm by itself, but provides an easy way to disable
all XS code by switching back to a regular sort.
Perl 5.6 and earlier used a quicksort algorithm to implement sort. That
algorithm was not stable, so could go quadratic. (A stable sort
preserves the input order of elements that compare equal. Although
quicksort's run time is O(NlogN) when averaged over all arrays of length
N, the time can be O(N**2), quadratic behavior, for some inputs.)
In 5.7, the quicksort implementation was replaced with a stable
mergesort algorithm whose worst-case behavior is O(NlogN). But
benchmarks indicated that for some inputs, on some platforms, the
original quicksort was faster.
5.8 has a sort pragma for limited control of the sort. Its rather blunt
control of the underlying algorithm may not persist into future Perls,
but the ability to characterize the input or output in implementation
independent ways quite probably will.
use default perl version
METHODS
xsort
API that allow you to use one of the XS subroutines. Prefer using this
method. ( view optimization section for tricks )
list
provide a reference to an array if only one argument is provided can
be ommit
my $list = [ 1, 3, 2, 5, 4 ];
xsort( $list ) or xsort( list => $list )
algorithm [ optional, default = quick ]
default value is quick you can use any of the following choices
quick # quicksort
heap # heapsort
merge
insertion # not recommended ( slow )
perl # use standard perl sort method instead of c implementation
data [ optional, default = integer ]
You can specify which kind of sort you are expecting ( i.e. '<=>' or
'cmp' ) by setting this attribute to one of these two values
integer # <=>, is the default operator if not specified
string # cmp, do the compare on string
quick_sort
XS subroutine to perform the quicksort algorithm. No type checking
performed. Accept only one single argument as input.
my $list = [1, 6, 4, 2, 3, 5 ]
Sort::XS::quick_sort($list);
heap_sort
XS subroutine to perform the heapsort algorithm. No type checking
performed. Accept only one single argument as input.
my $list = [1, 6, 4, 2, 3, 5 ]
Sort::XS::heap_sort($list);
merge_sort
XS subroutine to perform the mergesort algorithm. No type checking
performed. Accept only one single argument as input.
my $list = [1, 6, 4, 2, 3, 5 ]
Sort::XS::merge_sort($list)
insertion_sort
XS subroutine to perform the insertionsort algorithm. No type checking
performed. Accept only one single argument as input.
my $list = [1, 6, 4, 2, 3, 5 ]
Sort::XS::insertion_sort($list);
OPTIMIZATION
xsort provides an api to call xs subroutines to easy change sort
preferences and an easy way to use it ( adding data checking ) as it
provides an extra layer on the top of xs subroutines it has a cost...
and adds a little more slowness... This extra cost cannot be noticed on
large arrays ( > 100 rows ), but for very small arrays ( ~ 10 rows ) it
will not a good idea to use the api ( at least at this stage ). In this
case you will prefer to do a direct call to one of the XS methods to
have pure performance.
Note that all the XS subroutines are not exported by default.
my $list = [1, 6, 4, 2, 3, 5 ]
Sort::XS::quick_sort($list);
Sort::XS::heap_sort($list);
Sort::XS::merge_sort($list)
Sort::XS::insertion_sort($list);
Once again, if you use large arrays, it will be better to use :
xsort([100..1]);
BENCHMARK
Here is a glance of what you can expect using this module :
These results have been computed on a set of multiple random arrays
generated by the benmark test included in the dist testsuite.
# sorting an ( integer ) array of 10 rows - quicksort is 12 % faster
than a regular perl sort
# sorting an ( integer ) array of 100 rows - quicksort is 46 % faster
than a regular perl sort
# sorting an ( integer ) array of 1_000 rows - quicksort is 82 % faster
than a regular perl sort
# sorting an ( integer ) array of 10_000 rows - quicksort is 2 x times
faster than a regular perl sort ( 112 % )
# sorting an ( integer ) array of 100_000 rows - quicksort is 2.5 x
times faster than a regular perl sort
# sorting an ( integer ) array of 1_000_000 rows - quicksort is 3.4 x
times faster than a regular perl sort
CONTRIBUTE
You can contribute to this project via GitHub :
https://github.com/atoomic/Sort-XS
TODO
Implementation of float, string comparison... At this time only
implement sort of integers
Improve API performance for small set of arrays
AUTHOR
Nicolas R.,
COPYRIGHT AND LICENSE
This software is copyright (c) 2011 by eboxr.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.