Source code for chatterbot.logic.mathematical_evaluation
from chatterbot.logic import LogicAdapter
from chatterbot.conversation import Statement
from chatterbot import languages
[docs]
class MathematicalEvaluation(LogicAdapter):
"""
The MathematicalEvaluation logic adapter parses input to determine
whether the user is asking a question that requires math to be done.
If so, the equation is extracted from the input and returned with
the evaluated result.
For example:
User: 'What is three plus five?'
Bot: 'Three plus five equals eight'
:kwargs:
* *language* (``object``) --
The language is set to ``chatterbot.languages.ENG`` for English by default.
"""
def __init__(self, chatbot, **kwargs):
super().__init__(chatbot, **kwargs)
self.language = kwargs.get('language', languages.ENG)
self.cache = {}
def can_process(self, statement):
"""
Determines whether it is appropriate for this
adapter to respond to the user input.
"""
response = self.process(statement)
self.cache[statement.text] = response
return response.confidence == 1
def process(self, statement, additional_response_selection_parameters=None):
"""
Takes a statement string.
Returns the equation from the statement with the mathematical terms solved.
"""
from mathparse import mathparse
input_text = statement.text
# Use the result cached by the process method if it exists
if input_text in self.cache:
cached_result = self.cache[input_text]
self.cache = {}
return cached_result
# Getting the mathematical terms within the input statement
expression = mathparse.extract_expression(input_text, language=self.language.ISO_639.upper())
response = Statement(text=expression)
try:
response.text = '{} = {}'.format(
response.text,
mathparse.parse(expression, language=self.language.ISO_639.upper())
)
# The confidence is 1 if the expression could be evaluated
response.confidence = 1
except mathparse.PostfixTokenEvaluationException:
response.confidence = 0
return response
