Build your own Chatbot with Python

In this tutorial, I will show you how to build your very own chatbot using Python. There are broadly two variants of chatbots, Rule-based and Self-learning.

A rule-based bot uses some rules on which it is trained, while a self-learning bot uses some machine-learning-based approach to chat.

In this tutorial, I will show you how to create a simple and quick chatbot in python using a rule-based approach.

Lets Import the libraries

from nltk.chat.util import Chat, reflections

Create the chatbots list of recognizable patterns and it’s a response to those patterns. To do this we will create a variable called pairs.

#Pairs is a list of patterns and responses.
pairs = [
    [
        r"(.*)my name is (.*)",
        ["Hello %2, How are you today ?",]
    ],
    [
        r"(.*)help(.*) ",
        ["I can help you ",]
    ],
     [
        r"(.*) your name ?",
        ["My name is thecleverprogrammer, but you can just call me robot and I'm a chatbot .",]
    ],
    [
        r"how are you (.*) ?",
        ["I'm doing very well", "i am great !"]
    ],
    [
        r"sorry (.*)",
        ["Its alright","Its OK, never mind that",]
    ],
    [
        r"i'm (.*) (good|well|okay|ok)",
        ["Nice to hear that","Alright, great !",]
    ],
    [
        r"(hi|hey|hello|hola|holla)(.*)",
        ["Hello", "Hey there",]
    ],
    [
        r"what (.*) want ?",
        ["Make me an offer I can't refuse",]
        
    ],
    [
        r"(.*)created(.*)",
        ["Aman Kharwal created me using Python's NLTK library ","top secret ;)",]
    ],
    [
        r"(.*) (location|city) ?",
        ['New Delhi, India',]
    ],
    [
        r"(.*)raining in (.*)",
        ["No rain in the past 4 days here in %2","In %2 there is a 50% chance of rain",]
    ],
    [
        r"how (.*) health (.*)",
        ["Health is very important, but I am a computer, so I don't need to worry about my health ",]
    ],
    [
        r"(.*)(sports|game|sport)(.*)",
        ["I'm a very big fan of Cricket",]
    ],
    [
        r"who (.*) (Cricketer|Batsman)?",
        ["Virat Kohli"]
    ],
    [
        r"quit",
        ["Bye for now. See you soon :) ","It was nice talking to you. See you soon :)"]
    ],
    [
        r"(.*)",
        ['That is nice to hear']
    ],
]

Okay, so as we finished the patterns and responses, let’s take a look at something called reflections. Reflections is a dictionary file that contains a set of input values and corresponding output values.

For example, if the string input was “I am a programmer”, then the output would be “you are a programmer”.

print(reflections)

#Output
{'i am': 'you are',
'i was': 'you were',
'i': 'you',
"i'm": 'you are',
"i'd": 'you would',
"i've": 'you have',
"i'll": 'you will',
'my': 'your',
'you are': 'I am',
'you were': 'I was',
"you've": 'I have',
"you'll": 'I will',
'your': 'my',
'yours': 'mine',
'you': 'me',
'me': 'you'}

We can also create our own reflections dictionary in the same format as reflections above. Below is an example of how to do this:

my_dummy_reflections= {
    "go"     : "gone",
    "hello"    : "hey there"
}

Now let’s print a default message, and finish our chatbot:

#default message at the start of chat
print("Hi, I'm thecleverprogrammer and I like to chat\nPlease type lowercase English language to start a conversation. Type quit to leave ")
#Create Chat Bot
chat = Chat(pairs, reflections)