def calcNgramSim(a, b):
num_shared_ngrams = len(a.intersection(b))
#num_all_ngrams = len(a.difference(b)) + len(b.difference(a)) + num_shared_ngrams
num_all_ngrams = len(list(a)) + len(list(b)) - num_shared_ngrams
if num_all_ngrams != 0:
sim = NGram.ngram_similarity(num_shared_ngrams, num_all_ngrams)
else:
sim = 0
return sim
