def create_trie(
post_list
): # post_list is a map whose keys are document IDs and values are the words in that document
all_words = set()
for words in post_list.values():
for word in words:
all_words.add(word)
root = Trie.Node('', [], [])
for word in all_words:
current = root
for i in range(len(word)):
char = word[i]
index = Trie.find(
current.children_letters, char
) # check if the children of our current node contains this char
if index == -1: # this sequence has not been added so we need to add this char into a child node
pos = bisect.bisect_left(current.children_letters,
char) # find the position to insert
bisect.insort(current.children_letters, char)
node = Trie.Node(char, [], [])
current.children_nodes.insert(
pos, node) # insert into the same position
current = node
else: # this sequence is already added so move to that node
current = current.children_nodes[index]
if i == len(word) - 1: current.is_terminal = True
return root
def test_is_on_edge(self):
# \
# 0001 - 1001
# \
# - 0011
root = Trie.Node(word.epsilon, None)
branch = Trie.Node(word(0b0001, 4), root)
root.set_child(branch)
child1 = Trie.Node(word(0b1001, 4), branch)
branch.set_child(child1)
child2 = Trie.Node(word(0b0011, 4), branch)
branch.set_child(child2)
# edge cases
q = word(0b1, 1)
res = root.is_on_edge(q)
self.assertFalse(res)
q = word.epsilon
res = root.is_on_edge(q)
self.assertTrue(res)
# on edge
q = word(0b0, 1)
res = branch.is_on_edge(q)
self.assertTrue(res)
q = word(0b0001, 4)
res = branch.is_on_edge(q)
self.assertTrue(res)
q = word(0b0000, 4)
res = branch.is_on_edge(q)
self.assertFalse(res)
q = word(0b000110, 6)
res = child1.is_on_edge(q)
self.assertTrue(res)
q = word(0b00011001, 8)
res = child1.is_on_edge(q)
self.assertTrue(res)
q = word(0b000100, 6)
res = child1.is_on_edge(q)
self.assertFalse(res)
q = word(0b00010000, 8)
res = child1.is_on_edge(q)
self.assertFalse(res)
# to long
q = word(0b00011, 5)
res = branch.is_on_edge(q)
self.assertFalse(res)
q = word(0b000010, 6)
res = branch.is_on_edge(q)
self.assertFalse(res)
# to short
q = word.epsilon
res = branch.is_on_edge(q)
self.assertFalse(res)
q = word(0b000, 3)
res = child1.is_on_edge(q)
self.assertFalse(res)
# no matching prefix
q = word(0b01001, 5)
res = child1.is_on_edge(q)
self.assertFalse(res)