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# NAME

Sort::Key::Natural - fast natural sorting

# SYNOPSIS

    use Sort::Key::Natural qw(natsort);

    my @data = qw(foo1 foo23 foo6 bar12 bar1
                  foo bar2 bar-45 foomatic b-a-r-45);

    my @sorted = natsort @data;

    print "@sorted\n";
    # prints:
    #   b-a-r-45 bar1 bar2 bar12 bar-45 foo foo1 foo6 foo23 foomatic

    use Sort::Key::Natural qw(natkeysort);

    my @objects = (...);
    my @sorted = natkeysort { $_->get_id } @objects;

# DESCRIPTION

This module extends the [Sort::Key](/doc/Sort%3A%3AKey) family of modules to support
natural sorting.

Under natural sorting, strings are split at word and number
boundaries, and the resulting substrings are compared as follows:

- numeric substrings are compared numerically
- alphabetic substrings are compared lexically
- numeric substrings come always before alphabetic substrings

Spaces, symbols and non-printable characters are only considered for
splitting the string into its parts but not for sorting. For instance
`foo-bar-42` is broken in three substrings `foo`, `bar` and `42`
and after that the dashes are ignored.

Note, that the sorting is case sensitive. To do a case insensitive
sort you have to convert the keys explicitly:

    my @sorted = natkeysort { lc $_ } @data

Also, once this module is loaded, the new type `natural` (or `nat`) will
be available from [Sort::Key::Maker](/doc/Sort%3A%3AKey%3A%3AMaker). For instance:

    use Sort::Key::Natural;
    use Sort::Key::Maker i_rnat_keysort => qw(integer -natural);

creates a multi-key sorter `i_rnat_keysort` accepting two keys, the
first to be compared as an integer and the second in natural
descending order.

There is also an alternative set of natural sorting functions that
recognize floating point numbers. They use the key type `natwf`
(abbreviation of `natural_with_floats`).

## FUNCTIONS

the functions that can be imported from this module are:

- natsort @data

    returns the elements of `@data` sorted in natural order.

- rnatsort @data

    returns the elements of `@data` sorted in natural descending order.

- natkeysort { CALC\_KEY($\_) } @data

    returns the elements on `@array` naturally sorted by the keys
    resulting from applying them `CALC_KEY`.

- rnatkeysort { CALC\_KEY($\_) } @data

    is similar to `natkeysort` but sorts the elements in descending
    order.

- natsort\_inplace @data
- rnatsort\_inplace @data
- natkeysort\_inplace { CALC\_KEY($\_) } @data
- rnatkeysort\_inplace { CALC\_KEY($\_) } @data

    these functions are similar respectively to `natsort`, `rnatsort`,
    `natsortkey` and `rnatsortkey`, but they sort the array `@data` in
    place.

- $key = mkkey\_natural $string

    given `$string`, returns a key that can be compared lexicographically
    to another key obtained in the same manner, results in the same order
    as comparing the former strings as in the natural order.

    If the argument `$key` is not provided it defaults to `$_`.

- natwfsort @data
- rnatwfsort @data
- natwfkeysort { CALC\_KEY($\_) } @data
- rnatwfkeysort { CALC\_KEY($\_) } @data
- natwfsort\_inplace @data
- rnatwfsort\_inplace @data
- natwfkeysort\_inplace { CALC\_KEY($\_) } @data
- rnatwfkeysort\_inplace { CALC\_KEY($\_) } @data
- mkkey\_natural\_with\_floats $key

    this ugly named set of functions perform in the same way as its
    s/natwf/nat/ counterpart with the difference that they honor floating
    point numbers embedded inside the strings.

    In this context a floating point number is a string matching the
    regular expression `/[+\-]?\d+(\.\d*)?/`. Note that numbers with an
    exponent part (i.e. `1.12E-12`) are not recognized as such.

    Note also that numbers without an integer part (i.e. `.2` or `-.12`)
    are not supported either.

# SEE ALSO

[Sort::Key](/doc/Sort%3A%3AKey), [Sort::Key::Maker](/doc/Sort%3A%3AKey%3A%3AMaker).

Other module providing similar functionality is [Sort::Naturally](/doc/Sort%3A%3ANaturally).

# COPYRIGHT AND LICENSE

Copyright (C) 2006, 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.