skipdict

Python dictionary object permanently sorted by value.

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A skip dict is a Python dictionary which is permanently sorted by value. This package provides a fast, idiomatic implementation written in C – based on Redis’ sorted sets.

The data structure uses a skip list internally.

An example use is a leaderboard where the skip dict provides very fast access to the score of each user, the position and the current top users.

Usage

The skip dict works just like a normal dictionary except its values must be numbers:

from skipdict import SkipDict

skipdict = SkipDict()
skipdict['foo'] = 1.0
skipdict['bar'] = 2.0

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 filter based on value:

>>> skipdict.keys(min=2.0)
['bar']

In addition, the index attribute is a view that provides both key lookup and slicing on position:

>>> skipdict.index(2.0)          # What's the first key that has value 2.0?
'bar'
>>> skipdict.index[-1]           # What key has the highest value?
'bar'
>>> skipdict.index[-1:].items()  # What key and value is highest?
[('bar', 2.0)]