NLTK Performance

Question

Alright, I've been pretty interested in natural language processing recently: however, I've used C until now for most of my work. I heard of NLTK, and I didn't know Python, but it seems quite easy to learn, and it's looking like a really powerful and interesting language. In particular, the NLTK module seems very, very adapted to what I need to do.

However, when using sample code for NLTK and pasting that into a file called test.py, I've noticed it takes a very, very long time to run !

I'm calling it from the shell like so:

time python ./test.py

And on a 2.4 GHz machine with 4 GBs of RAM, it takes 19.187 seconds !

Now, maybe this is absolutely normal, but I was under the impression that NTLK was extremely fast; I may have been mistaken, but is there anything obvious that I'm clearly doing wrong here?

Answer 1

@Jacob is right about conflating training and tagging time. I've simplified the sample code a little and here's the time breakdown:

Importing nltk takes 0.33 secs
Training time: 11.54 secs
Tagging time: 0.0 secs
Sorting time: 0.0 secs

Total time: 11.88 secs

System:

CPU: Intel(R) Core(TM)2 Duo CPU E8400 @ 3.00GHz
Memory: 3.7GB

Code:

import pprint, time
startstart = time.clock()

start = time.clock()
import nltk
print "Importing nltk takes", str((time.clock()-start)),"secs"

start = time.clock()
tokenizer = nltk.tokenize.RegexpTokenizer(r'\w+|[^\w\s]+')
tagger = nltk.UnigramTagger(nltk.corpus.brown.tagged_sents())
print "Training time:",str((time.clock()-start)),"secs"


text = """Mr Blobby is a fictional character who featured on Noel
Edmonds' Saturday night entertainment show Noel's House Party,
which was often a ratings winner in the 1990s. Mr Blobby also
appeared on the Jamie Rose show of 1997. He was designed as an
outrageously over the top parody of a one-dimensional, mute novelty
character, which ironically made him distinctive, absurd and popular.
He was a large pink humanoid, covered with yellow spots, sporting a
permanent toothy grin and jiggling eyes. He communicated by saying
the word "blobby" in an electronically-altered voice, expressing
his moods through tone of voice and repetition.

There was a Mrs. Blobby, seen briefly in the video, and sold as a
doll.

However Mr Blobby actually started out as part of the 'Gotcha'
feature during the show's second series (originally called 'Gotcha
Oscars' until the threat of legal action from the Academy of Motion
Picture Arts and Sciences[citation needed]), in which celebrities
were caught out in a Candid Camera style prank. Celebrities such as
dancer Wayne Sleep and rugby union player Will Carling would be
enticed to take part in a fictitious children's programme based around
their profession. Mr Blobby would clumsily take part in the activity,
knocking over the set, causing mayhem and saying "blobby blobby
blobby", until finally when the prank was revealed, the Blobby
costume would be opened - revealing Noel inside. This was all the more
surprising for the "victim" as during rehearsals Blobby would be
played by an actor wearing only the arms and legs of the costume and
speaking in a normal manner.[citation needed]"""

start = time.clock()
tokenized = tokenizer.tokenize(text)
tagged = tagger.tag(tokenized)
print "Tagging time:",str((time.clock()-start)),"secs"

start = time.clock()
tagged.sort(lambda x,y:cmp(x[1],y[1]))
print "Sorting time:",str((time.clock()-start)),"secs"

#l = list(set(tagged))
#pprint.pprint(l)
print
print "Total time:",str((time.clock()-startstart)),"secs"