NLTK性能

Question

好吧，我最近对自然语言处理很感兴趣:然而，我到现在为止大部分工作都使用了C。我听说过NLTK，我不知道Python，但它似乎很容易学习，而且它看起来是一种非常强大和有趣的语言。特别是，NLTK模块似乎非常非常适合我需要做的工作。

但是，当使用NLTK示例代码并将其粘贴到一个名为test.py的文件中时，我注意到运行它需要非常非常长的时间！

我是从壳里说出来的：

time python ./test.py

在一个2.4GB内存的GHz机器上，它需要19.187秒！

现在，也许这是完全正常的，但我的印象是NTLK是非常快，我可能是错了，但有什么明显的，我做错了吗？

Answer 1

我相信你把训练时间和处理时间混为一谈。训练一个模型，如UnigramTagger，可能需要很长时间。所以可以从磁盘上的泡菜文件中加载经过训练的模型。但是，一旦将模型加载到内存中，处理就会相当快。请参阅我在用NLTK标记词类上的文章底部的“分类器效率”一节，以了解不同标记算法的处理速度。

Answer 2

雅各布把训练和标记时间混为一谈是对的。我已经稍微简化了样本代码，下面是时间分解：

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

系统：

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

代码：

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"