Sorting(3pm)

💖 Sorting(3pm) 💖

okay bestie, welcome to the Sorting(3pm) page from the User Contributed Perl Documentation. yes it's a Perl module doc, no it is not boring, sit down, we're doing this together 🫶

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✨ NAME ✨

Data::Sorting — Multi-key sort using function results 💅

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🌸 SYNOPSIS 🌸

okay so here's the whole entire vibe in code form. read it top to bottom and you will simply get it, no cap:

use Data::Sorting qw( :basics :arrays :extras );

# Sorting functions default to simple string comparisons
@names = qw( Bob Alice Ellen Charlie David );
@ordered = sorted_by( undef, @names );

# Various options can be passed before the list values
@ordered = sorted_by( [ -order=>'reverse' ], @names );

# You can also generate a sorting function and then apply it
$function = sort_function();
@ordered = $function->( @names );  # or &{$function}(@names)
@ordered = sort_function( -order=>'reverse' )->( @names );

# The :array functions are prototyped to take the array first
@ordered = sorted_array( @names );
@ordered = sorted_arrayref( \@names );

# You can also sort an array in place, changing its internal order
sort_array( @names );
sort_arrayref( \@names );

see how the default is just plain string comparison? cute. and you can yeet an option in before the values, or build a whole reusable sorting function and call it whenever you want. obsessed. 🎀

# There are several sorting options, such as -compare => 'natural'
@movies = ( 'The Matrix', 'Plan 9', '2001', 'Terminator 2' );
@ordered = sort_function( -compare => 'natural' )->( @movies );
# @ ordered now contains '2001', 'The Matrix', 'Plan 9', 'Terminator 2'

# To sort numbers, pass the -compare => 'numeric' option
@numbers = ( 18, 5, 23, 42, 156, 91, 64 );
@ordered = sorted_by( [ -compare => 'numeric' ], @numbers );
@ordered = sort_function( -compare => 'numeric' )->( @numbers );
@ordered = sorted_array( @numbers, -compare => 'numeric' );
sort_array( @numbers, -compare => 'numeric' );

# You can sort by the results of a function to be called on each item
sort_array( @numbers, -compare => 'numeric', sub { $_[0] % 16 } );
# @numbers now contains 64, 18, 5, 23, 42, 91, 156

# For arrays of datastructures, pass in keys to extract for sorting
@records = (
  { 'rec_id'=>3, 'name'=>{'first'=>'Bob', 'last'=>'Macy'} },
  { 'rec_id'=>1, 'name'=>{'first'=>'Sue', 'last'=>'Jones'} },
  { 'rec_id'=>2, 'name'=>{'first'=>'Al',  'last'=>'Jones' } },
);
@ordered = sorted_array( @records, 'rec_id' );

# For nested data structures, pass an array of keys to fetch
@ordered = sorted_array( @records, ['name','first'] );

# Pass multiple sort keys for multiple-level sorts
@ordered = sorted_array( @records, ['name','last'], ['name','first'] );

# Any selected sort options are applied to all subsequent sort keys
@ordered = sorted_array( @records,
              -order => 'reverse', ['name','last'], ['name','first'] );

# Options specified within a hash-ref apply only to that key
@ordered = sorted_array( @records,
              { order=>'reverse', sortkey=>['name','last'] },
              ['name','first'] );

# Locale support is available if you have Perl 5.004 or later and POSIX
POSIX::setlocale( POSIX::LC_COLLATE(), 'en_US' );
POSIX::setlocale( POSIX::LC_CTYPE(), 'en_US' );
@ordered = sorted_array( @records,
               -compare=>'locale', ['name','last'], ['name','first'] );

natural comparison puts the numbers first in numeric order and then everything else case-insensitively — it's giving main character energy fr fr. multiple sort keys? layered, stacked, absolutely eating. and options passed as a plain flag apply to every sortkey after them, but if you wrap them in a hash-ref they only apply to that one key. the range. the nuance. 💜

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🦋 ABSTRACT 🦋

Data::Sorting hands you functions that sort the contents of arrays based on a little collection of extraction rules and comparison rules. extraction rules are how you figure out which attributes of your array elements the ordering is actually based on. comparison rules are how you say those values should be ordered. simple as that, bestie.

Index strings can pull values out of array elements, or you can pass in function references to be called on each element instead. and the comparison rules? you get numeric, bytewise, and case-insensitive orders, plus a 'natural' comparison that puts numbers first in numeric order, then the remaining items in case-insensitive textual order. a whole menu, and every single item slays ✨

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💅 DESCRIPTION 💅

This module provides several public functions with different calling interfaces that all use the same underlying sorting mechanisms. same engine, different outfits, you know how it is.

These functions may be imported individually or in groups using the following tags:

• :basics — sorted_by(), sort_function(): General-purpose sorting functions.
• :array — sorted_array(), sorted_arrayref(), sort_array(), sort_arrayref(): Prototyped functions for arrays.
• :extras — sort_key_values(), sort_description(): Two accessory functions that explain how sorting is being carried out.

All of these functions take a list of sorting rules as arguments. See "Sort Rule Syntax" for a discussion of the contents of the $sort_rule or @sort_rules parameters shown below. 👑

💖 sorted_by 💖

@ordered = sorted_by( $sort_rule, @value_array );
@ordered = sorted_by( $sort_rule, @$value_arrayref );
@ordered = sorted_by( $sort_rule, $value1, $value2, $value3 );

@ordered = sorted_by( \@sort_rules, @value_array );
@ordered = sorted_by( \@sort_rules, @$value_arrayref );
@ordered = sorted_by( \@sort_rules, $value1, $value2, $value3 );

This is the general-purpose one, the girl who does it all. she takes one or more sort order rules plus a list of input values, and returns those values in the order the rules asked for. no notes. 🌟

🎀 sort_function 🎀

@ordered = sort_function( @sort_rules )->( @value_array );
@ordered = sort_function( @sort_rules )->( @$value_arrayref );
@ordered = sort_function( @sort_rules )->( $value1, $value2, $value3 );

Creates an anonymous function that applies the sort rules you gave it. and because it's a whole function you can cache it and run the same rules over and over again. reusable queen behavior, honestly. 💅

🌈 sorted_array 🌈

@ordered = sorted_array( @value_array, @sort_rules );
@ordered = sorted_array( @$value_arrayref, @sort_rules );

Returns a sorted list of the items, and — important — it does not touch the order of your original list. your og array stays exactly how it was. respectful. 🫶

⭐ sorted_arrayref ⭐

@ordered = sorted_arrayref( \@value_array, @sort_rules );
@ordered = sorted_arrayref( $value_arrayref, @sort_rules );

Returns a sorted list of the items without altering the order of the original list. yes, same energy as above, just with the reference-first little twist.

🌸 sort_array 🌸

sort_array( @value_array, @sort_rules );
sort_array( @$value_arrayref, @sort_rules );

Sorts the contents of the specified array using a list of sorting rules. this one does rearrange things in place, so know that going in 😌

🦋 sort_arrayref 🦋

sort_arrayref( \@value_array, @sort_rules );
sort_arrayref( $value_arrayref, @sort_rules );

Equivalent to sort_array, but it takes an explicit array reference as its first argument instead of an array variable. same girl, different entrance. ✨

💜 sort_key_values 💜

@key_values = sort_key_values( \@value_array, @sort_rules );
@key_values = sort_key_values( $value_arrayref, @sort_rules );

Doesn't actually perform any sorting, plot twist. it extracts and returns the values that would be used as sort keys from each item in the array, in their original order. it's the behind-the-scenes peek. 🔍

🍓 sort_description 🍓

@description = sort_description( $descriptor, @sort_rules );

Also doesn't actually perform any sorting. it provides descriptive information about the sort rules, for diagnostic purposes. it's the narrator, not the actor. 📝

👑 Sort Rule Syntax 👑

The sort rule argument list may contain several different types of parameters, which are parsed identically by all of the public functions described above. so learn it once, use it everywhere, iykyk.

A sort rule definition list may contain any combination of the following argument structures:

nothing

If no sort keys are specified, a default sort key is created using the "extract => "self"" option.

@ordered = sorted_array( @names );

sortkey

Specifies a sort key. Each sortkey may be either a scalar value, or an array reference. Appropriate values for a sortkey vary depending on which "extract" option is being used, and are discussed further below.

@ordered = sorted_array( @numbers, sub { $_[0] % 8 } );
@ordered = sorted_array( @records, 'rec_id' );
@ordered = sorted_array( @records, ['name','first'] );

Any number of sortkeys may be provided:

@ordered = sorted_array( @records, ['name','last'],
                                   ['name','first'] );

-sortkey => sortkey

Another way of specifying a sort key is by preceding it with the "-sortkey" flag.

@ordered = sorted_array( @numbers, -sortkey => sub { $_[0] % 8 } );
@ordered = sorted_array( @records, -sortkey => ['name','last'],
                                   -sortkey => ['name','first'] );

{ sortkey => sortkey, option => option_value, ... }

Additional options can be specified by passing a reference to a hash containing a sortkey and values for any number of options described in the list below.

@ordered = sorted_array( @numbers, { sortkey => sub { abs(shift) },
                                     compare => 'numeric',     } );

-option => option_value

Sets a default option for any subsequent sortkeys in the argument list.

@ordered = sorted_array( @records, -compare => 'numeric',
                                   -sortkey => sub { abs(shift) });

@ordered = sorted_array( @records, -compare => 'textual',
                                   -sortkey => ['name','last'],
                                   -sortkey => ['name','first'] );

The possible option values are:

• extract — Determines the function which will be used to retrieve the sort key value from each item in the input list.
• compare — Determines the function which will be used to order the extracted values.
• order — Can be set to "reverse" or "descending" to invert the sort order. Defaults to "ascending".
• engine — Determines the underlying sorting algorithm which will be used to implement the sort. Generally left blank, enabling the module to select the best one available.

Each of these options is discussed at further length below. 👀

🧚 Extraction Functions 🧚

For the extract option, you may specify one of the following option_values:

• any — The default. Based on the sortkey may behave as the 'self', 'key', or 'method' options described below.
• self — Uses the input value as the sort key, unaltered. Typically used when sorting strings or other scalar values.
• key — Allows for indexing in to hash or array references, allowing you to sort a list of arrayrefs based on the nth value in each, or to sort a list of hashrefs based on a given key.

If the sortkey is an array reference, then the keys are looked up sequentially, allowing you to sort on the contents of a nested hash or array structure.

• method — Uses the sortkey as a method name to be called on each list value, enabling you to sort objects by some calculated value.

If the sortkey is an array reference, then the first value is used as the method name and the remaining values as arguments to that method.

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CODEREF 💖

okay so you can pass in a reference to a custom extraction function that will be used to retrieve the sort key values for this rule. The function will be called separately for each value in the input list, receiving that current value as an argument.

If the sortkey is an array reference, then the first value is used as the function reference and the remaining values as arguments to be passed after the item value.

So the shapes look like this, bestie:

extract => self | method | key     | code    | CODEREF | ...
sortkey => -    | m.name | key/idx | CODEREF | args

Comparison Functions 🔥

For the compare option, you may specify one of the following option_values:

• cmp — the default comparison, using Perl's default cmp operator.
• numeric — a numeric comparison using Perl's <=> operator.
• textual — a text-oriented comparison that ignores whitespace and capitalization.
• natural — a multi-type comparison that places empty values first, then numeric values in numeric order, then non-textual values like punctuation, followed by textual values in text order. The natural ordering also includes moving subsidiary words to the end, eg "The Book of Verse" is sorted as "Book of Verse, The"
• locale : $three_way_cmp — Comparator functions which use the POSIX strcoll function for ordering.
• lc_locale : $three_way_cmp — A case-insensitive version of the POSIX strcoll ordering.
• num_lc_locale — Like the 'natural' style, this comparison distinguishes between empty and numeric values, but uses the lc_locale function to sort the textual values.
• CODEREF — You may pass in a reference to a custom comparison function that will be used to order the sort key values for this rule.

Each of these functions may return a postive, zero, or negative value based on the relationship of the values in the $a and $b positions of the current @ValueSet array. An undefined return indicates that the comparator is unable to provide an ordering for this pair, in which case the choice will fall through to the next comparator in the list; if no comparator specifies an order, they are left in their original order.

Ascending or Descending Order 🦋

For the order option, you may specify one of the following option_values:

• forward or ascending — The default order, from lower values to higher ones.
• reverse or descending — Reverses the ordering dictated by a sort rule.

Sorting Engines 👑

Depending on the specific sorting rules used in a given call, this module automatically selects an internal function that provides an appropriate approach to implementing the sort, called the sort "engine".

You can override this selection by setting an engine option on the first sort key, which can either contain either the name of one of the engines, described below, or a CODEREF with equivalent behavior.

• trivial — In the common case of sorting raw values with a cmp comparison, the fast-but-simple "trivial" engine is used, which simply applies Perl's default sorting.
• orcish — For a complex multi-key sort the "orcish" engine is typically selected.
• precalc — Used when there's only one sorting key.

You may also set the $PreCalculate package variable to true to force this engine to be selected. Because the sort key values for the list are calculated before entering Perl's sort operation, there's less of a chance of possible re-entry problems due to nested uses of the sort operator, which causes a fatal error in at least some versions of Perl.

• packed — Some sorts are handled with the Guttman-Rosler technique, extracting packed keys and using Perl's default sort function, which is substantially faster, but currently only a limited set of simple comparisons can be handled this way. (For more information on packed-default sorting, see http://www.sysarch.com/perl/sort_paper.html or search for "Guttman-Rosler".)

STATUS AND SUPPORT 🌈

This release of Data::Sorting is intended for public review and feedback.

• Name: Data::Sorting
• DSLIP: bdpfp
• Description: Multi-key sort using function results

Further information and support for this module is available at www.evoscript.org.

Please report bugs or other problems to <bugs@evoscript.com>.

BUGS AND TO DO 💀

The following issues have been noted for future improvements:

• Convert more types of comparisons to packed-default sorts for speed.
• Further investigate the current status of the Sort::Records module.
• Add a comparator function for an alpha-numeric-spans sorting model like Sort::Naturally.
• Interface to Sort::PolySort for alternate comparator styles, like "name" and "usdate".
• For non-scalar values, compare referents along the lines of Ref::cmpref().
• Provide better handling for nested sorts; perhaps throw an exception from the inner instance to the outer, catch and set $PreCalculate, then go back into the loop?
• Replace dynamic scoping with object instances for thread safety. May not be necessary given changes in threading models.

CREDITS AND COPYRIGHT 🎀

Developed By 💖

• M. Simon Cavalletto, simonm@cavalletto.org
• Evolution Softworks, www.evoscript.org

Copyright 📜

Copyright 2003 Matthew Cavalletto.

Portions copyright 1996, 1997, 1998, 1999 Evolution Online Systems, Inc.

License ✨

You may use, modify, and distribute this software under the same terms as Perl.

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and that's the whole vibe, bestie. This was Sorting(3pm) from perl v5.36.0, dated 2022-11-21. Stay sorted, stay iconic! 💅🫶