def insert(self,word):
currNode=self.startNode
self.startNode.incTCounter()
for char in word:
prevNode=currNode
if(not prevNode.getNext(char)):
currNode=Node(prevNode.getString()+char)
currNode.setTCounter(1)
prevNode.setNext(char,currNode)
else:
currNode=prevNode.getNext(char)
currNode.incTCounter()
currNode.setIsWord(True)
currNode.incWCounter()
class Trie():
# Constructor
def __init__(self,words):
self.startNode=Node("")
for word in words:
self.insert(word)
# test membership includes substrings of words
# that are not real words
def isMember(self,string):
currNode=self.startNode
if string == "":
return True
for letter in string:
if(not currNode.getNext(letter)):
return False
else:
currNode=currNode.getNext(letter)
return True
# test if word is a real word (word that was inserted or initialized)
def isRealWord(self,word):
if (self.isMember(word)):
return self.getNode(word).getIsWord()
else:
return False
# returns the node searched or an empty node not in the trie
# containing string "Node Not Found"
def getNode(self,word):
if (self.isMember(word)):
if word == "":
return self.startNode
currNode=self.startNode
counter = 0
for letter in word:
currNode=currNode.getNext(letter)
if (counter == len(word)-1):
return currNode
counter = counter + 1
else:
return Node("Node Not Found")
# insert a word into the trie
def insert(self,word):
currNode=self.startNode
self.startNode.incTCounter()
for char in word:
prevNode=currNode
if(not prevNode.getNext(char)):
currNode=Node(prevNode.getString()+char)
currNode.setTCounter(1)
prevNode.setNext(char,currNode)
else:
currNode=prevNode.getNext(char)
currNode.incTCounter()
currNode.setIsWord(True)
currNode.incWCounter()
# update frequency of a word if in trie
# returns true on success / false if word not found
def setFreqKey(self,word, freq):
if (self.isMember(word)):
currNode=self.startNode
for char in word:
currNode=currNode.getNext(char)
currNode.setCounter(currNode.getWCounter() + freq)
return True
else:
return False
def setFreq(self,word,freq):
if (self.setFreqKey(word, freq)):
return self.setFreqKey(word[:-1], -1*freq)
else:
return False
# return a list of (letter,frequency) tuples [(letter, freq), ...]
def getFreq(self,word):
currNode=self.startNode
freqList = []
for char in word:
currNode=currNode.getNext(char)
freqList.append((currNode.getString(), currNode.getCounter()))
return freqList
