https://github.com/malthe/skipdict

A skip dict is a Python dictionary which is permanently sorted by value.
https://github.com/malthe/skipdict

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A skip dict is a Python dictionary which is permanently sorted by value.

• Host: GitHub
• URL: https://github.com/malthe/skipdict
• Owner: malthe
• License: bsd-2-clause
• Created: 2014-09-15T23:19:53.000Z (over 10 years ago)
• Default Branch: master
• Last Pushed: 2014-09-25T23:01:39.000Z (about 10 years ago)
• Last Synced: 2024-11-01T22:42:58.630Z (about 2 months ago)
• Language: C
• Size: 188 KB
• Stars: 19
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.rst
  • Changelog: CHANGES.rst
  • License: LICENSE

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README

        
SkipDict

========

A skip dict is a Python dictionary which is permanently sorted by

value. This package provides a fast, idiomatic implementation written

in C with an extensive test suite.

The data structure uses a `skip list

`_ internally.

An example use is a leaderboard where the skip dict provides

logarithmic access to the score and ranking of each user, as well as

efficient iteration in either direction from any node.

Compatible with Python 2.7+ and Python 3.3+.

Usage

-----

The skip dict works just like a normal dictionary except it maps only

to floating point values::

  from skipdict import SkipDict

  skipdict = SkipDict(maxlevel=4)

  skipdict['foo'] = 1.0

  skipdict['bar'] = 2.0

The ``SkipDict`` optionally takes a dictionary or a sequence of

``(key, value)`` pairs::

  skipdict = SkipDict({'foo': 1.0, 'bar': 2.0})

  skipdict = SkipDict(('foo', 1.0), ('bar', 1.0), ('bar', 1.0))

Note that duplicates are automatically aggregated to a sum. To

illustrate this, we can count the occurrences of letters in a text::

  skipdict = SkipDict(

      (char, 1) for char in

      "Everything popular is wrong. - Oscar Wilde"

  )

  # The most frequent letter is a space.

  skipdict.keys()[-1] == " "

The ``skipdict`` is sorted by value which means that iteration and

standard mapping protocol methods such as ``keys()``, ``values()`` and

``items()`` return items in sorted order.

Each of these methods have been extended with optional range arguments

``min`` and ``max`` which limit iteration based on value. In addition,

the iterator objects support the item and slice protocols:

>>> skipdict.keys(min=2.0)[0]

'bar'

>>> skipdict.keys(max=2.0)[1:]

['bar']

Note that the methods always return an iterator. Use ``list`` to

expand to a sequence:

>>> iterator = skipdict.keys()

>>> list(iterator)

['bar']

The ``index(value)`` method returns the first key that has exactly the

required value. If the value is not found then a ``KeyError``

exception is raised.

>>> skipdict.index(2.0)

'bar'

Alternatives

------------

Francesco Romani wrote `pyskiplist

`_ which also provides an

implementation of the skip list datastructure for CPython written

in C.

Paul Colomiets wrote `sortedsets

`_ which is an implementation

in pure Python. The randomized test cases were adapted from this

package.

License

-------

Copyright (c) 204 Malthe Borch 

This software is provided "as-is" under the BSD License.