Function to divide a word into groups of vowels or consonants.

stemming.py

class PorterStemmer(AbstractStemmer):
    consonants = "bcdfghjklmnpqrstwxz"
    special_case = "y"
    vowels = "aeiou"
    
    def _divide_into_groups(self, word):
        groups = []
        preceding = ""
        for idx, letter in enumerate(word.lower()):
            if preceding == "":
                preceding = letter
            else:
                if self._compare_same_class(preceding, letter):
                    preceding+= letter
                    if idx == len(word)-1:
                        groups.append(preceding)
                else:
                    groups.append(preceding)
                    preceding = letter
                    if idx == len(word)-1:
                        groups.append(letter)
        return groups
    
    def _compare_same_class(self, l1, l2):
        if l1 in self.consonants and l2 in self.consonants:
            return True
        elif l1 in self.vowels and l2 in self.vowels:
            return True
        else:
            return False
        return False