Not sure what I should write here. The code should be self-explanatory.

"""This is a data definition class--Searchable_list. Searchable_list takes a list of strings and makes it searchable. Searchable meaning you can find which elements in the list have a pattern. """ class Searchable_list(object): """this will make your word list searchable. Note, It will also loose the original order of the list.""" def __init__(self, lis): assert hasattr(lis,"__iter__") self.search_dict=dict() for word in set(lis):self.add_word(word) def add_word(self,word): """this will add a word to the search_dict search dict is of the form: {letter:{nextletter:{(index,word)}}} """ assert type(word) is str#or isinstance(word,str) for index,val in enumerate(word[:-1]): next_letter=self.search_dict.setdefault(val,dict()) words_list=next_letter.setdefault(word[index+1],set())#object modification words_list.add((index,word))#object modifification def find_matches(self,seq): """finds all the words in the list with this sequence. Uses '.' as wildcard. """ s_d=self.search_dict assert len(seq)>1 #could put a try catch to catch key errors for index,letter in enumerate(seq[:-1]): if not(letter=="."and seq[index+1]=="."): #no point if they all match... if letter==".": L_m=set.union(*(i.get(seq[index+1],set()) for i in s_d.values())) #.get is important here. not all is have i[seq[index+1]] elif seq[index+1]==".": L_m=set.union(*(i for i in s_d[letter].values())) else: L_m=s_d[letter].get(seq[index+1],{})#this is a set. #L_m==letter_matches if index>0: m_m=((i-index,word) for i,word in L_m) #m_m=matches_matches. These words still have the pattern. #your matching all indexes to the original m_s m_s.intersection_update(m_m) #m_s=matches_set else: m_s=L_m.copy() #http://stackoverflow.com/questions/23200969/how-to-clone-or-copy-a-set-in-python return m_s 

EDIT: Because this post was bumped, and I've added some pretty major improvements to it here's a link to the final version of this. It's not very clean, but it has optimizations this doesn't have. If there's an interest I can try to put some comments explaining the optimizations in the github or post something here about it (probably in the form of another answer). https://github.com/user-name-is-taken/words-with-friends/blob/master/WWF_DDC.py (note, the scrabble stuff is just adapting this code for scrabble). For now, the basic idea behind the optimizations is that python's set.intersection is faster than set.union