NAME
Sort::Key - the fastest way to sort anything in Perl
SYNOPSIS
use Sort::Key qw(keysort nkeysort ikeysort);
@by_name = keysort { "$_->{surname} $_->{name}" } @people;
# sorting by a numeric key:
@by_age = nkeysort { $_->{age} } @people;
# sorting by a numeric integer key:
@by_sons = ikeysort { $_->{sons} } @people;
DESCRIPTION
Sort::Key provides a set of functions to sort lists of values by some calculated key value.
It is faster (usually much faster) and uses less memory than other alternatives implemented around perl sort function (ST, GRT, etc.).
Multi-key sorting functionality is also provided via the companion modules Sort::Key::Multi, Sort::Key::Maker and Sort::Key::Register.
FUNCTIONS
This module provides a large number of sorting subroutines but they are all variations off the keysort
one:
@sorted = keysort { CALC_KEY($_) } @data
that is conceptually equivalent to
@sorted = sort { CALC_KEY($a) cmp CALC_KEY($b) } @data
and where CALC_KEY($_)
can be any expression to extract the key value from $_
(not only a subroutine call).
For instance, some variations are nkeysort
that performs a numeric comparison, rkeysort
that orders the data in descending order, ikeysort
and ukeysort
that are optimized versions of nkeysort
that can be used when the keys are integers or unsigned integers respectively, etc.
Also, inplace versions of the sorters are provided. For instance
keysort_inplace { CALC_KEY($_) } @data
that is equivalent to
@data = keysort { CALC_KEY($_) } @data
but being (a bit) faster and using less memory.
The full list of subroutines that can be imported from this module follows:
- keysort { CALC_KEY } @array
-
returns the elements on
@array
sorted by the key calculated applying{ CALC_KEY }
to them.Inside
{ CALC_KEY }
, the object is available as$_
.For example:
@a=({name=>john, surname=>smith}, {name=>paul, surname=>belvedere}); @by_name=keysort {$_->{name}} @a;
This function honours the
use locale
pragma. - nkeysort { CALC_KEY } @array
-
similar to
keysort
but compares the keys numerically instead of as strings.This function honours the
use integer
pragma, i.e.:use integer; my @s=(2.4, 2.0, 1.6, 1.2, 0.8); my @ns = nkeysort { $_ } @s; print "@ns\n"
prints
0.8 1.6 1.2 2.4 2
- rnkeysort { CALC_KEY } @array
-
works as
nkeysort
, comparing keys in reverse (or descending) numerical order. - ikeysort { CALC_KEY } @array
-
works as
keysort
but compares the keys as integers (32 bits or more, no checking is performed for overflows). - rikeysort { CALC_KEY } @array
-
works as
ikeysort
, but in reverse (or descending) order. - ukeysort { CALC_KEY } @array
-
works as
keysort
but compares the keys as unsigned integers (32 bits or more).For instance, it can be used to efficiently sort IP4 addresses:
my @data = qw(1.2.3.4 4.3.2.1 11.1.111.1 222.12.1.34 0.0.0.0 255.255.255.0) 127.0.0.1); my @sorted = ukeysort { my @a = split /\./; (((($a[0] << 8) + $a[1] << 8) + $a[2] << 8) + $a[3]) } @data;
- rukeysort { CALC_KEY } @array
-
works as
ukeysort
, but in reverse (or descending) order. - keysort_inplace { CALC_KEY } @array
- nkeysort_inplace { CALC_KEY } @array
- ikeysort_inplace { CALC_KEY } @array
- ukeysort_inplace { CALC_KEY } @array
- rkeysort_inplace { CALC_KEY } @array
- rnkeysort_inplace { CALC_KEY } @array
- rikeysort_inplace { CALC_KEY } @array
- rukeysort_inplace { CALC_KEY } @array
-
work as the corresponding
keysort
functions but sorting the array inplace. - rsort @array
- nsort @array
- rnsort @array
- isort @array
- risort @array
- usort @array
- rusort @array
- rsort_inplace @array
- nsort_inplace @array
- rnsort_inplace @array
- isort_inplace @array
- risort_inplace @array
- usort_inplace @array
- rusort_inplace @array
-
are simplified versions of its
keysort
cousins. They use the own values as the sorting keys.For instance those constructions are equivalent:
@sorted = nsort @foo; @sorted = nkeysort { $_ } @foo; @sorted = sort { $a <=> $b } @foo;
- multikeysorter(@types)
- multikeysorter_inplace(@types)
- multikeysorter(\&genkeys, @types)
- multikeysorter_inplace(\&genkeys, @types)
-
are the low level interface to the multi-key sorting functionality (normally, you should use Sort::Key::Maker and Sort::Key::Register or Sort::Key::Multi instead).
They get a list of keys descriptions and return a reference to a multi-key sorting subroutine.
Types accepted by default are:
string, str, locale, loc, integer, int, unsigned_integer, uint, number, num
and support for additional types can be added via the register_type subroutine available from Sort::Key::Types or the more friendly interface available from Sort::Key::Register.
Types can be preceded by a minus sign to indicate descending order.
If the first argument is a reference to a subroutine it is used as the multi-key extraction function. If not, the generated sorters expect one as their first argument.
Example:
my $sorter1 = multikeysorter(sub {length $_, $_}, qw(int str)); my @sorted1 = &$sorter1(qw(foo fo o of oof)); my $sorter2 = multikeysorter(qw(int str)); my @sorted2 = &$sorter2(sub {length $_, $_}, qw(foo fo o of oof));
SEE ALSO
perl sort function, integer, locale.
Companion modules Sort::Key::Multi, Sort::Key::Register, Sort::Key::Maker and Sort::Key::Natural.
Sort::Key::IPv4, Sort::Key::DateTime and Sort::Key::OID modules add support for additional datatypes to Sort::Key.
Sort::Key::External allows to sort huge lists that do not fit in the available memory.
Other interesting Perl sorting modules are Sort::Maker, Sort::Naturally and Sort::External.
SUPPORT
To report bugs, send me and email or use the CPAN bug tracking system at http://rt.cpan.org.
Commercial support
Commercial support, professional services and custom software development around this module are available through my current company. Drop me an email with a rough description of your requirements and we will get back to you ASAP.
My wishlist
If you like this module and you're feeling generous, take a look at my Amazon Wish List: http://amzn.com/w/1WU1P6IR5QZ42
COPYRIGHT AND LICENSE
Copyright (C) 2005-2007, 2012, 2014 by Salvador Fandiño, <sfandino@yahoo.com>.
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.4 or, at your option, any later version of Perl 5 you may have available.