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Python

# Natural Language Toolkit: Chatbot Utilities
#
# Copyright (C) 2001-2020 NLTK Project
# Authors: Steven Bird <stevenbird1@gmail.com>
# URL: <http://nltk.org/>
# For license information, see LICENSE.TXT
# Based on an Eliza implementation by Joe Strout <joe@strout.net>,
# Jeff Epler <jepler@inetnebr.com> and Jez Higgins <jez@jezuk.co.uk>.
import re
import random
reflections = {
"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",
}
class Chat(object):
def __init__(self, pairs, reflections={}):
"""
Initialize the chatbot. Pairs is a list of patterns and responses. Each
pattern is a regular expression matching the user's statement or question,
e.g. r'I like (.*)'. For each such pattern a list of possible responses
is given, e.g. ['Why do you like %1', 'Did you ever dislike %1']. Material
which is matched by parenthesized sections of the patterns (e.g. .*) is mapped to
the numbered positions in the responses, e.g. %1.
:type pairs: list of tuple
:param pairs: The patterns and responses
:type reflections: dict
:param reflections: A mapping between first and second person expressions
:rtype: None
"""
self._pairs = [(re.compile(x, re.IGNORECASE), y) for (x, y) in pairs]
self._reflections = reflections
self._regex = self._compile_reflections()
def _compile_reflections(self):
sorted_refl = sorted(self._reflections, key=len, reverse=True)
return re.compile(
r"\b({0})\b".format("|".join(map(re.escape, sorted_refl))), re.IGNORECASE
)
def _substitute(self, str):
"""
Substitute words in the string, according to the specified reflections,
e.g. "I'm" -> "you are"
:type str: str
:param str: The string to be mapped
:rtype: str
"""
return self._regex.sub(
lambda mo: self._reflections[mo.string[mo.start() : mo.end()]], str.lower()
)
def _wildcards(self, response, match):
pos = response.find("%")
while pos >= 0:
num = int(response[pos + 1 : pos + 2])
response = (
response[:pos]
+ self._substitute(match.group(num))
+ response[pos + 2 :]
)
pos = response.find("%")
return response
def respond(self, str):
"""
Generate a response to the user input.
:type str: str
:param str: The string to be mapped
:rtype: str
"""
# check each pattern
for (pattern, response) in self._pairs:
match = pattern.match(str)
# did the pattern match?
if match:
resp = random.choice(response) # pick a random response
resp = self._wildcards(resp, match) # process wildcards
# fix munged punctuation at the end
if resp[-2:] == "?.":
resp = resp[:-2] + "."
if resp[-2:] == "??":
resp = resp[:-2] + "?"
return resp
# Hold a conversation with a chatbot
def converse(self, quit="quit"):
user_input = ""
while user_input != quit:
user_input = quit
try:
user_input = input(">")
except EOFError:
print(user_input)
if user_input:
while user_input[-1] in "!.":
user_input = user_input[:-1]
print(self.respond(user_input))