I am using nltk to generate n-grams from sentences by first removing given stop words. However, nltk.pos_tag() is extremely slow taking up to 0.6 sec on my CPU (Intel i7).
The output:
['The first time I went, and was completely taken by the live jazz band and atmosphere, I ordered the Lobster Cobb Salad.']
0.620481014252
["It's simply the best meal in NYC."]
0.640982151031
['You cannot go wrong at the Red Eye Grill.']
0.644664049149
The code:
for sentence in source:
nltk_ngrams = None
if stop_words is not None:
start = time.time()
sentence_pos = nltk.pos_tag(word_tokenize(sentence))
print time.time() - start
filtered_words = [word for (word, pos) in sentence_pos if pos not in stop_words]
else:
filtered_words = ngrams(sentence.split(), n)
Is this really that slow or am I doing something wrong here?
Use pos_tag_sents for tagging multiple sentences:
>>> import time
>>> from nltk.corpus import brown
>>> from nltk import pos_tag
>>> from nltk import pos_tag_sents
>>> sents = brown.sents()[:10]
>>> start = time.time(); pos_tag(sents[0]); print time.time() - start
0.934092998505
>>> start = time.time(); [pos_tag(s) for s in sents]; print time.time() - start
9.5061340332
>>> start = time.time(); pos_tag_sents(sents); print time.time() - start
0.939551115036