pombredanne / pygtrie

pygtrie

pygtrie is a Python library implementing a trie data structure.

Trie data structure, also known as radix or prefix tree, is a tree associating keys to values where all the descendants of a node have a common prefix (associated with that node).

The trie module contains Trie, CharTrie and StringTrie classes each implementing a mutable mapping interface, i.e. dict interface. As such, in most circumstances, Trie could be used as a drop-in replacement for a dict, but the prefix nature of the data structure is trie’s real strength.

The module also contains PrefixSet class which uses a trie to store a set of prefixes such that a key is contained in the set if it or its prefix is stored in the set.

Features

• A full mutable mapping implementation.
• Supports iterating over as well as deleting a subtrie.
• Supports prefix checking as well as shortest and longest prefix look-up.
• Extensible for any kind of user-defined keys.
• A PrefixSet supports “all keys starting with given prefix” logic.
• Can store any value including None.

Installation

To install pygtrie, run:

pip install pygtrie

Or download the sources and save pygtrie.py file with your project.

Upgrading from 0.9.x

The 1.0 release introduced backwards incompatibility in naming. The module has been renamed from trie to pygtrie. Fortunately, updating scripts using pygtrie should boil down to replacing:

from pytrie import trie

with:

import pygtrie as trie