128 lines
3.8 KiB
Python
128 lines
3.8 KiB
Python
# Natural Language Toolkit: Chatbot Utilities
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#
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# Copyright (C) 2001-2019 NLTK Project
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# Authors: Steven Bird <stevenbird1@gmail.com>
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# URL: <http://nltk.org/>
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# For license information, see LICENSE.TXT
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# Based on an Eliza implementation by Joe Strout <joe@strout.net>,
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# Jeff Epler <jepler@inetnebr.com> and Jez Higgins <jez@jezuk.co.uk>.
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import re
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import random
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from six.moves import input
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reflections = {
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"i am": "you are",
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"i was": "you were",
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"i": "you",
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"i'm": "you are",
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"i'd": "you would",
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"i've": "you have",
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"i'll": "you will",
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"my": "your",
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"you are": "I am",
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"you were": "I was",
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"you've": "I have",
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"you'll": "I will",
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"your": "my",
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"yours": "mine",
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"you": "me",
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"me": "you",
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}
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class Chat(object):
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def __init__(self, pairs, reflections={}):
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"""
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Initialize the chatbot. Pairs is a list of patterns and responses. Each
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pattern is a regular expression matching the user's statement or question,
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e.g. r'I like (.*)'. For each such pattern a list of possible responses
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is given, e.g. ['Why do you like %1', 'Did you ever dislike %1']. Material
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which is matched by parenthesized sections of the patterns (e.g. .*) is mapped to
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the numbered positions in the responses, e.g. %1.
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:type pairs: list of tuple
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:param pairs: The patterns and responses
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:type reflections: dict
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:param reflections: A mapping between first and second person expressions
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:rtype: None
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"""
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self._pairs = [(re.compile(x, re.IGNORECASE), y) for (x, y) in pairs]
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self._reflections = reflections
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self._regex = self._compile_reflections()
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def _compile_reflections(self):
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sorted_refl = sorted(self._reflections.keys(), key=len, reverse=True)
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return re.compile(
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r"\b({0})\b".format("|".join(map(re.escape, sorted_refl))), re.IGNORECASE
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)
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def _substitute(self, str):
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"""
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Substitute words in the string, according to the specified reflections,
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e.g. "I'm" -> "you are"
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:type str: str
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:param str: The string to be mapped
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:rtype: str
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"""
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return self._regex.sub(
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lambda mo: self._reflections[mo.string[mo.start() : mo.end()]], str.lower()
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)
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def _wildcards(self, response, match):
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pos = response.find("%")
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while pos >= 0:
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num = int(response[pos + 1 : pos + 2])
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response = (
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response[:pos]
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+ self._substitute(match.group(num))
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+ response[pos + 2 :]
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)
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pos = response.find("%")
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return response
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def respond(self, str):
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"""
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Generate a response to the user input.
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:type str: str
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:param str: The string to be mapped
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:rtype: str
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"""
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# check each pattern
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for (pattern, response) in self._pairs:
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match = pattern.match(str)
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# did the pattern match?
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if match:
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resp = random.choice(response) # pick a random response
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resp = self._wildcards(resp, match) # process wildcards
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# fix munged punctuation at the end
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if resp[-2:] == "?.":
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resp = resp[:-2] + "."
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if resp[-2:] == "??":
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resp = resp[:-2] + "?"
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return resp
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# Hold a conversation with a chatbot
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def converse(self, quit="quit"):
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user_input = ""
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while user_input != quit:
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user_input = quit
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try:
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user_input = input(">")
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except EOFError:
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print(user_input)
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if user_input:
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while user_input[-1] in "!.":
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user_input = user_input[:-1]
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print(self.respond(user_input))
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