Dictionary Tree

.gitignore

*.pyc

README.md

Dictionary Tree

Given a tuple, it creates a tree with nested dictionaries and then finally the respective counts for the sequence for the number of times it appears.

Sample Run

dct = {} 
incr_dict(dct, ('a', 'b', 'c')) 
dct # {'a': {'b': {'c': 1}}} 

incr_dict(dct, ('a', 'b', 'c')) 
dct # {'a': {'b': {'c': 2}}} 

incr_dict(dct, ('a', 'b', 'f')) 
dct # {'a': {'b': {'c': 2, 'f': 1}}} 

incr_dict(dct, ('a', 'r', 'f')) 
dct # {'a': {'r': {'f': 1}, 'b': {'c': 2, 'f': 1}}} 

incr_dict(dct, ('a', 'z')) 
dct # {'a': {'r': {'f': 1}, 'b': {'c': 2,'f': 1}, 'z': 1}} 

dict_tree.py

def incr_dict(dictionary, elements):
	if len(elements) == 0:
		return
	updated = dictionary
	for element in elements[:-1]:
		if element not in updated:
			updated[element] = {}
		updated = updated[element]

	if elements[-1] not in updated:
		updated[elements[-1]] = 1
	else:
		updated[elements[-1]] += 1

dict_tree_test.py

import unittest

from dict_tree import incr_dict

class TestIncrDict(unittest.TestCase):
	def setUp(self):
		self.dict = {}
		incr_dict(self.dict, ('a', 'b', 'c'))

	def tearDown(self):
		self.dict = None

	def test_empty_sequence(self):
		dct = {}
		incr_dict(dct, ())
		self.assertEqual(dct, {})

	def test_adding_initial_sequence(self):
		self.assertEqual(self.dict, {'a': {'b': {'c': 1}}})

	def test_adding_the_same_sequence(self):
		incr_dict(self.dict, ('a', 'b', 'c'))
		self.assertEqual(self.dict, {'a': {'b': {'c': 2}}})

	def test_adding_a_sequence_that_with_different_leaf_node(self):
		incr_dict(self.dict, ('a', 'b', 'f'))
		self.assertEqual(self.dict, {'a': {'b': {'c': 1, 'f': 1}}})

	def test_adding_a_sequence_that_with_different_middle_node(self):
		incr_dict(self.dict, ('a', 'r', 'c'))
		self.assertEqual(self.dict, {'a': {'b': {'c': 1}, 'r': {'c': 1}}})

	def test_adding_shorter_sequence(self):
		incr_dict(self.dict, ('a', 'z'))
		self.assertEqual(self.dict, {'a': {'b': {'c': 1}, 'z': 1}})

if __name__ == '__main__':
	unittest.main()