sort::key::maker(3pm) [debian man page]
Sort::Key::Maker(3pm) User Contributed Perl Documentation Sort::Key::Maker(3pm) NAME
Sort::Key::Maker - multikey sorter creator SYNOPSYS
# create a function that sorts strings by length: use Sort::Key::Maker sort_by_length => sub { length $_}, qw(integer); # create a multikey sort function; # first key is integer sorted in descending order, # second key is a string in default (ascending) order: use Sort::Key::Maker ri_s_keysort => qw(-integer string); # some sample data... my @foo = qw(foo bar t too tood mama); # and now, use the sorter functions previously made: # get the values on @foo sorted by length: my @sorted = sort_by_length @foo; # sort @foo inplace by its length and then by its value: ri_s_keysort_inplace { length $_, $_ } @foo; DESCRIPTION
Sort::Key::Maker is a pragmatic module that provides an easy to use interface to Sort::Key multikey sorting functionality. It creates multikey sorting functions on the fly for any key type combination and exports them to the caller package. The key types natively accepted are: string, str, locale, loc, integer, int, unsigned_integer, uint, number, num and support for other types can be added via Sort::Key::Register (or also via Sort::Key::register_type()). USAGE use Sort::Key::Maker foo_sort => @keys; exports two subroutines to the caller package: "foo_sort (&@)" and "foo_sort_inplace (&@)". Those two subroutines require a sub reference as their first argument and then respectively, the list to be sorted or an array. For instance: use Sort::Key::Maker bar_sort => qw(int int str); @bar=qw(doo tomo 45s tio); @sorted = bar_sort { unpack "CCs", $_ } @bar; # or sorting @bar inplace bar_sort_inplace { unpack "CCs", $_ } @bar; use Sort::Key::Maker foo_sort => &genmultikey, @keys; when the first argument after the sorter name is a reference to a subroutine it is used as the multikey extraction function. The generated sorter functions doesn't require neither accept one, i.e.: use Sort::Key::Maker sort_by_length => sub { length $_ }, 'int'; my @sorted = sort_by_length qw(foo goo h mama picasso); SEE ALSO
Sort::Key, Sort::Key::Register. Sort::Maker also available from CPAN provides similar functionality. AUTHOR
Salvador Fandin~o, <sfandino@yahoo.com> COPYRIGHT AND LICENSE
Copyright (C) 2005 by Salvador Fandin~o 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. perl v5.14.2 2010-04-16 Sort::Key::Maker(3pm)
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Sort::Key::Top(3pm) User Contributed Perl Documentation Sort::Key::Top(3pm) NAME
Sort::Key::Top - select and sort top n elements SYNOPSIS
use Sort::Key::Top (nkeytop top); # select 5 first numbers by absolute value: @top = nkeytop { abs $_ } 5 => 1, 2, 7, 5, 5, 1, 78, 0, -2, -8, 2; # ==> @top = (1, 2, 1, 0, -2) # select 5 first numbers by absolute value and sort accordingly: @top = nkeytopsort { abs $_ } 5 => 1, 2, 7, 5, 5, 1, 78, 0, -2, -8, 2; # ==> @top = (0, 1, 1, 2, -2) # select 5 first words by lexicographic order: @a = qw(cat fish bird leon penguin horse rat elephant squirrel dog); @top = top 5 => @a; # ==> @top = qw(cat fish bird elephant dog); DESCRIPTION
The functions available from this module select the top n elements from a list using several common orderings and custom key extraction procedures. They are all variations around keytopsort { CALC_KEY($_) } $n => @data; In array context, this function calculates the ordering key for every element in @data using the expression inside the block. Then it selects and orders the $n elements with the lower keys when compared lexicographically. It is equivalent to the pure Perl expression: (sort { CALC_KEY($a) cmp CALC_KEY($b) } @data)[0 .. $n-1]; If $n is negative, the last $n elements from the bottom are selected: topsort 3 => qw(foo doom me bar doz hello); # ==> ('bar', 'doz', 'doom') topsort -3 => qw(foo doom me bar doz hello); # ==> ('foo', 'hello', 'me') top 3 => qw(foo doom me bar doz hello); # ==> ('doom', 'bar', 'doz') top -3 => qw(foo doom me bar doz hello); # ==> ('foo', 'me', 'hello') In scalar context, the value returned by the functions on this module is the cutoff value allowing to select nth element from the array. For instance: # n = 5; scalar(topsort 5 => @data) eq (sort @data)[4] # true # n = -5; scalar(topsort -5 => @data) eq (sort @data)[-5] # true Note that on scalar context, the "sort" variations (see below) are usually the right choice: scalar topsort 3 => qw(me foo doz doom me bar hello); # ==> 'doz' scalar top 3 => qw(me foo doz doom me bar hello); # ==> 'bar' Note also, that the index is 1-based (it starts at one instead of at zero). The "atpos" set of functions explained below do the same and are 0-based. Variations allow to: - use the own values as the ordering keys topsort 5 => qw(a b ab t uu g h aa aac); # ==> a aa aac ab b - return the selected values in the original order top 5 => qw(a b ab t uu g h aa aac); # ==> a b ab aa aac - use a different ordering For instance comparing the keys as numbers, using the locale configuration or in reverse order: rnkeytop { length $_ } 3 => qw(a ab aa aac b t uu g h); # ==> ab aa aac rnkeytopsort { length $_ } 3 => qw(a ab aa aac b t uu g h); # ==> aac ab aa A prefix is used to indicate the required ordering: (no prefix) lexicographical ascending order r lexicographical descending order l lexicographical ascending order obeying locale configuration r lexicographical descending order obeying locale configuration n numerical ascending order rn numerical descending order i numerical ascending order but converting the keys to integers first ri numerical descending order but converting the keys to integers first u numerical ascending order but converting the keys to unsigned integers first ru numerical descending order but converting the keys to unsigned integers first - select the head element from the list sorted nhead 6, 7, 3, 8, 9, 9; # ==> 3 nkeyhead { length $_ } qw(a ab aa aac b t uu uiyii) # ==> 'a' - select the tail element from the list sorted tail qw(a ab aa aac b t uu uiyii); # ==> 'uu' nkeytail { length $_ } qw(a ab aa aac b t uu uiyii) # ==> 'uiyii' - select the element at position n from the list sorted atpos 3, qw(a ab aa aac b t uu uiyii); # ==> 'ab'; rnkeyatpos { abs $_ } 2 => -0.3, 1.1, 4, 0.1, 0.9, -2; # ==> 1.1 rnkeyatpos { abs $_ } -2 => -0.3, 1.1, 4, 0.1, 0.9, -2; # ==> -0.3 Note that for the atpos set of functions indexes start at zero. - return a list composed by the elements with the first n ordered keys and then the remaining ones. ikeypart { length $_ } 3 => qw(a bbbb cc ddddd g fd); # ==> a cc g bbbb ddddd fd - return two arrays references, the first array containing the elements with the first n ordered keys and the second with the rest. keypartref { length $_ } 3 => qw(a bbbb cc ddddd g fd); # ==> [a cc g] [bbbb ddddd fd] The full list of available functions is: top ltop ntop itop utop rtop rltop rntop ritop rutop keytop lkeytop nkeytop ikeytop ukeytop rkeytop rlkeytop rnkeytop rikeytop rukeytop topsort ltopsort ntopsort itopsort utopsort rtopsort rltopsort rntopsort ritopsort rutopsort keytopsort lkeytopsort nkeytopsort ikeytopsort ukeytopsort rkeytopsort rlkeytopsort rnkeytopsort rikeytopsort rukeytopsort head lhead nhead ihead uhead rhead rlhead rnhead rihead ruhead keyhead lkeyhead nkeyhead ikeyhead ukeyhead rkeyhead rlkeyhead rnkeyhead rikeyhead rukeyhead tail ltail ntail itail utail rtail rltail rntail ritail rutail keytail lkeytail nkeytail ikeytail ukeytail rkeytail rlkeytail rnkeytail rikeytail rukeytail atpos latpos natpos iatpos uatpos ratpos rlatpos rnatpos riatpos ruatpos keyatpos lkeyatpos nkeyatpos ikeyatpos ukeyatpos rkeyatpos rlkeyatpos rnkeyatpos rikeyatpos rukeyatpos part lpart npart ipart upart rpart rlpart rnpart ripart rupart keypart lkeypart nkeypart ikeypart ukeypart rkeypart rlkeypart rnkeypart rikeypart rukeypart SEE ALSO
Sort::Key, "sort" in perlfunc. The Wikipedia article about selection algorithms <http://en.wikipedia.org/wiki/Selection_algorithm>. COPYRIGHT AND LICENSE
Copyright (C) 2006-2008, 2011 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 5.8.8 or, at your option, any later version of Perl 5 you may have available. perl v5.14.2 2011-06-17 Sort::Key::Top(3pm)