Un correcto culiao penca pal colega y la conchetumare.

correcto.py

# -*- coding: utf-8 -*-
from __future__ import print_function


sufix_noun_singular_plural = {
	'a': 'as', 'b': 'bes', 'c': 'cs', 'd': 'des', 'e': 'es', 'f': 'fs',
	'g': 'gs', 'i': 'is', 'j': 'jes', 'k': 'ks', 'l': 'les', 'm': 'ms',
	'n': 'nes', 'o': 'os', 'p': 'ps', 'r': 'res', 's': 'es', 't': 'ts',
	'u': 'us', 'v': 's', 'x': 'xes', 'z': 'ces'
}

article_plural = ['los', 'las', 'unas', 'unos']
article_singular = ['el', 'la', 'un', 'una']

articles = list()
articles.extend(article_plural)
articles.extend(article_singular)

female_noun_sufix = ['a', 'as', 'd', 'on', 'z', 'is', 'es', 'umbre']
male_noun_sufix = ['o', 'u', 'l', 'e', 'r']

def nv_mb_rule(word):
	"""
	Corrige word si este contiene nb o mv
	"""
	if 'nb' in word:
		word = word.replace('nb','nv')
	if 'mv' in word:
		word = word.replace('mv','mb')
	return word

def is_article(word):
	"""
	Verifica si word es un articulo
	"""
	if word in articles:
		return True
	else:
		return False

def is_plural_article(article):
	"""
	Verifica si el article es plural
	"""
	if article in article_plural:
		return True
	else:
		return False

def is_noun_plural(word):
	"""
	Verifica si word es un sustantivo plural
	"""
	for sufix in sufix_noun_singular_plural.values():
		if word.endswith(sufix):
			return True
		else:
			return False

def change_noun_to_singular(noun, sufix):
	"""
	Cambia el noun(sustantivo) a singular
	"""
	noun = noun[:-len(sufix)]
	return noun

def change_article_gender(article, noun, is_plural=False):
	"""
	Cambia de masculo a femenino o viceversa si es necesario 
	"""
	for sufix in female_noun_sufix:
		if noun.endswith(sufix):
			if is_plural:
				article = article.replace(article, 'las')
			else:
				article = article.replace(article, 'la')
			return article

	for sufix in male_noun_sufix:
		if noun.endswith(sufix):
			if is_plural:
				article = article.replace(article, 'los')
			else:
				article = article.replace(article, 'el')
			return article

	return article

raw_sentence = raw_input('introduzca una oración\n> ')
splited_sentence = raw_sentence.split()

splited_sentence[2] = nv_mb_rule(splited_sentence[2])

if is_article(splited_sentence[0]):  # Si la primera palabra es articulo.
	print('la sentencia comienza con un articulo')
	if not is_plural_article(splited_sentence[0]):  # Si el articulo es singular.
		# Cambiar sustantivo a singular 
		for sufix in sufix_noun_singular_plural.values():
			if splited_sentence[1].endswith(sufix):  # Si es un sustantivo plural
				print('el sustantivo sera cambiado a singular')
				splited_sentence[1] = change_noun_to_singular(splited_sentence[1], sufix)
				splited_sentence[0] = change_article_gender(splited_sentence[0], splited_sentence[1])
				break
			else:
				continue

	else:  # Si el articulo es plural
		# Verifica si el sustantivo es plural
		sufix_endswith = False
		for plural_sufix in sufix_noun_singular_plural.values():
			if splited_sentence[1].endswith(plural_sufix):
				sufix_endswith = True
				break
			else:
				continue

		# Cambia el sustantivo a plural
		if not sufix_endswith:
			for singular_sufix, plural_sufix in sufix_noun_singular_plural.iteritems():
				if splited_sentence[1].endswith(singular_sufix):
					splited_sentence[1] = splited_sentence[1][:-1] + plural_sufix
					break

		splited_sentence[0] = change_article_gender(splited_sentence[0], splited_sentence[1], is_plural=True)

	print(splited_sentence)

else:
	print('la sentencia no empieza con un articulo')