Naturally

Natural ("version number") sorting with support for:

• file names,
• legal document numbering,
• college course codes, and
• Unicode.

See Jeff Atwood's Sorting for Humans: Natural Sort Order.

Installation

$ gem install naturally

Usage

#sort

require 'naturally'

# Sort version numbers
Naturally.sort(["13.10", "13.04", "10.10", "10.04.4"])
          # => ["10.04.4", "10.10", "13.04", "13.10"]

# Sort legal section numbers
Naturally.sort(["336", "335a", "335", "335.1"])
          # => ["335", "335.1", "335a", "336"]

The library can also sort an array of objects:

# Define a new simple object for storing Ubuntu versions
UbuntuVersion = Struct.new(:name, :version)

# Create an array
releases = [
  UbuntuVersion.new('Saucy Salamander', '13.10'),
  UbuntuVersion.new('Raring Ringtail',  '13.04'),
  UbuntuVersion.new('Precise Pangolin', '12.04.4'),
  UbuntuVersion.new('Maverick Meerkat', '10.10'),
  UbuntuVersion.new('Quantal Quetzal',  '12.10'),
  UbuntuVersion.new('Lucid Lynx',       '10.04.4')
]

# Sort by the version attribute
Naturally.sort(releases, by: :version)

=> [#<struct UbuntuVersion name="Lucid Lynx",       version="10.04.4">,
    #<struct UbuntuVersion name="Maverick Meerkat", version="10.10">,
    #<struct UbuntuVersion name="Precise Pangolin", version="12.04.4">,
    #<struct UbuntuVersion name="Quantal Quetzal",  version="12.10">,
    #<struct UbuntuVersion name="Raring Ringtail",  version="13.04">,
    #<struct UbuntuVersion name="Saucy Salamander", version="13.10">]

More examples are in the specs.

#sort_filenames

Sorts filenames naturally, treating underscores and dots as separators. Useful for sorting files like images or documents that use numbers, underscores, and dots in their names.

files = [
  'abc_2.tif',
  'abc_1_a.tif',
  'abc_1.zzz',
  'abc_1_xyz.abc',
  'abc_2a.tif',
  'abc.2.tif',
  'abc.1_a.tif',
  'abc_2.abc',
  'abc_1_xyz.abc'
]
Naturally.sort_filenames(files)
# => [
#   "abc.1_a.tif",
#   "abc.2.tif",
#   "abc_1.zzz",
#   "abc_1_a.tif",
#   "abc_1_xyz.abc",
#   "abc_1_xyz.abc",
#   "abc_2.abc",
#   "abc_2.tif",
#   "abc_2a.tif"
# ]

This method gives higher priority to dots than underscores, so files like abc.1_a.tif will come before abc.2.tif.

Implementation Notes

The algorithm capitalizes on Ruby's array comparison behavior: Since each dotted number actually represents a hierarchical identifier, array comparison is a natural fit:

Arrays are compared in an “element-wise” manner; the first element of ary is compared with the first one of other_ary using the <=> operator, then each of the second elements, etc… As soon as the result of any such comparison is non zero (i.e. the two corresponding elements are not equal), that result is returned for the whole array comparison.

And so, when given input such as,

['1.9', '1.9a', '1.10']

...this module sorts the segmented numbers by comparing them in their array forms:

[['1', '9'], ['1', '9a'], ['1', '10']]

Finally, upon actual sort comparison, each of these strings is converted to an array of typed objects. This is to determine the sort order between heterogenous (yet ordered) segments such as '9a' and '9'.

The final nested comparison structure looks like this:

  [
   [
     [1], [9]
   ],
   [
     [1], [9, 'a']
   ],
   [
     [1], [10]
   ]
  ]

Related Work

• ahoward/version_sorter, the starting point for the naturally gem.
• GitHub's Version sorter

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request