nodetrie 1.0.1

Python bindings for NodeTrie, a trie data structure library

NodeTrie

A Trie data structure library.

Installation

pip install nodetrie

Motivation, design goals

NodeTrie is a Python extension to a native C library written for this purpose.

It came about from a lack of viable alternatives for Python. While other trie library implementations exist, they suffer from severe limitations such as

• Read only structures, no insertions

• High memory use for large trees

• Lack of searching, particularly file mask or wild card style searching

• Slow inserts

Existing implementations on PyPi fall into these broad categories, including Marissa-Trie (read only) and datrie (slow inserts, very high memory use).

NodeTrie’s C library is designed to minimize memory use as much as possible and still allow arbitrary length trees that can be searched.

Each node only has a name associated with it which is readonly on the Node object.

Node names are always returned as unicode by Node.name in Python 2/3.

On insertion, any python string type may be used whether a type of unicode or str, converted to byte strings on insertion if needed. The default encoding is utf-8.

Deletions are not implemented.

Example Usage

from nodetrie import Node

# This is the head of the trie, keep a reference to it
node = Node()

# Insert a linked tree so that a->b->c->d where -> means 'has child node'
node.insert_split_path(['a', 'b', 'c', 'd'])
node.children[0].name == 'a'
a_node = node.children[0]
a_node.name == 'a'
a_node.children[0].name == 'b'

# Insertions create only new nodes
# Insert linked tree so that a->b->c->dd
node.insert_split_path(['a', 'b', 'c', 'dd'])

# Only one 'a' node
len(node.children) == 1

# 'c' node has two children, 'd' and 'dd'
c_node = node.children[0].children[0].children[0]
len(c_node.children) == 2

Searching

NodeTrie supports exact name as well as file mask matching tree search.

from __future__ import print_function
from nodetrie import Node

node = Node()
for paths in [['a', 'b', 'c1', 'd1'], ['a', 'b', 'c1', 'd2'],
              ['a', 'b', 'c2', 'd1'], ['a', 'b', 'c2', 'd2']]:
    node.insert_split_path(paths)
for path, _node in node.search(node, ['a', 'b', '*', '*'], []):
    print(path, _node.name)

Output

[u'a', u'b', u'c1', u'd1'] d1
[u'a', u'b', u'c1', u'd2'] d2
[u'a', u'b', u'c2', u'd1'] d1
[u'a', u'b', u'c2', u'd2'] d2

A separator joined path list is return by the query function.

for match in node.query('a.b.*.*'):
    print(match)

for match in node.query('a|b|*|*', separator='|'):
   print(match)

Output

(u'a.b.c1.d1', <nodetrie.nodetrie.Node at 0x7f1899fa7730>),
(u'a.b.c1.d2', <nodetrie.nodetrie.Node at 0x7f1899fa7130>),
(u'a.b.c2.d1', <nodetrie.nodetrie.Node at 0x7f1899fa7110>),
(u'a.b.c2.d2', <nodetrie.nodetrie.Node at 0x7f1899fa73f0>)

(u'a|b|c1|d1', <nodetrie.nodetrie.Node object at 0x7f436d09c750>)
(u'a|b|c1|d2', <nodetrie.nodetrie.Node object at 0x7f436d09c770>)
(u'a|b|c2|d1', <nodetrie.nodetrie.Node object at 0x7f436d09c790>)
(u'a|b|c2|d2', <nodetrie.nodetrie.Node object at 0x7f436d09c7b0>)