Auto-complete feature using Trie

Algorithms Analysis of Algorithms Data Structure Algorithms

We have a Trie, and when a user enters a character, we have to show the matching string the Trie. This feature we call it as auto-completion. For example, if a Trie contains "xyzzzz,""xyz," "xxxyyxzzz" and when the user enter xy, then we have to show them xyzzzz, xyz, etc..,

Steps to achieve the result.

Search for the string using the standard Trie algorithm.
If the string is not present, then return -1.
If the string is present and is the end of a word in Trie, then print the string.
If the matching string doesn't have any node, then return.
Else print all the nodes.

Let's start coding.

# class for Trie Node
   class TrieNode():
   def __init__(self):
# initialising trie node
   self.trie_node = {}
   self.last_node = False
   class Trie():
   def __init__(self):
# initialising the trie
   self.root = TrieNode()
# list to store the words
   self.words = []
   def create_trie(self, keys):
# creating the Trie using data
   for key in keys:
# inserting one key to the trie
   self.insert_node(key)
   def insert_node(self, key):
   node = self.root
for obj in list(key):
   if not node.trie_node.get(obj):
   # creating a TrieNode
      node.trie_node[obj] = TrieNode()
      node = node.trie_node[obj]
   # making leaf node
   node.last_node = True
   def search(self, key):
# searching for the key
   node = self.root
   is_found = True
for obj in list(key):
   if not node.trie_node.get(obj):
      is_found = False
   break
      node = node.trie_node[obj]
return node and node.last_node and is_found
   def matches(self, node, word):
if node.last_node:
   self.words.append(word)
for obj, n in node.trie_node.items():
   self.matches(n, word + obj)
   def show_auto_completion(self, key):
   node = self.root
   is_found = False
   temp = ''
for obj in list(key):
   # checking the word
if not node.trie_node.get(obj):
   is_found = True
break
   temp += obj
   node = node.trie_node[obj]
if is_found:
   return 0
elif node.last_node and not node.trie_node:
   return -1
   self.matches(node, temp)
for string in self.words:
   print(string)
return 1
   # data for the Trie
strings = ["xyz", "xyzzzz", "xyabad", "xyyy", "abc", "abbccc", "xyx", "xyxer",
a"]
   # word for auto completion
   string = "xy"
   status = ["Not found", "Found"]
# instantiating Trie class
   trie = Trie()
# creating Trie using the strings
   trie.create_trie(strings)
# getting the auto completion words for the string from strings
   result = trie.show_auto_completion(string)
if result == -1 or result == 0:
   print("No matches")

If you run the above code, you will get the following result.

xyz
xyzzzz
xyabad
xyyy
xyx
xyxer

Hafeezul Kareem

Published on 21-Sep-2020 13:16:29

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