Sort::Key - the fastest way to sort anything in Perl 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; 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.). Multikey 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 expresion 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: 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. 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 { $_ } @s; print "@ns\n" prints 0.8 1.6 1.2 2.4 2 works as nkeysort, comparing keys in reverse (or descending) numerical order. works as keysort but compares the keys as integers (32 bits or more, no checking is performed for overflows). works as ikeysort, but in reverse (or descending) order. works as keysort but compares the keys as unsigned integers (32 bits or more). For instance, it can be used to efficiently sort IP4 addresses: my @data = qw(1.2.3.4 4.3.2.1 11.1.111.1 222.12.1.34 0.0.0.0 255.255.255.0) 127.0.0.1); my @sorted = ukeysort { my @a = split /\./; (((($a[0] << 8) + $a[1] << 8) + $a[2] << 8) + $a[3]) } @data; works as ukeysort, but in reverse (or descending) order. work as the corresponding keysort functions but sorting the array inplace. 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; are the low level interface to the multikey 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 multikey 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 non exportable register_type subroutine (see below) 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 multikey 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)); registers a new datatype named $name defining how to convert it to a multikey. &gensubkeys should convert the object of type $name passed on $_ to a list of values composing the multikey. @subkeystypes is the list of types for the generated multikeys. For instance: Sort::Key::register_type Person => sub { $_->surname, $_->name, $_->middlename }, qw(str str str); Sort::Key::register_type Color => sub { $_->R, $_->G, $_->B }, qw(int int int); Once a datatype has been registered it can be used in the same way as types supported natively, even for defining new types, i.e.: Sort::Key::register_type Family => sub { $_->man, $_->woman }, qw(Person Person); perl sort function, integer, locale. Companion modules Sort::Key::Multi, Sort::Key::Register, Sort::Key::Maker and Sort::Key::Natural. Other interesting Perl sorting modules are Sort::Maker and Sort::Natural. Copyright (C) 2005, 2006 by Salvador Fandin~o, <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.