python nltk 入门demo

sudo pip install -U pyyaml nltk

import nltk
nltk.download()

搞不定，必须代理：

Installing via a proxy web server¶

If your web connection uses a proxy server, you should specify the proxy address as follows. In the case of an authenticating proxy, specify a username and password. If the proxy is set to None then this function will attempt to detect the system proxy.

>>> nltk.set_proxy('http://proxy.example.com:3128', ('USERNAME', 'PASSWORD'))
>>> nltk.download()

然后下载：
输入d，下载模块，比如 stopwords等。

import nltk
from nltk.stem.lancaster import LancasterStemmer

def main():
    english_punctuations = set([',', '.', ':', ';', '?', '(', ')', '[', ']', '!', '@', '#', '%', '$', '*'])
    stemmer = LancasterStemmer()
    stopwords = set(nltk.corpus.stopwords.words('english'))

    sentence = """At eight o'clock on Thursday morning Arthur didn't feel very good. interesting booking store."""
    sentence = sentence.lower()
    tokens = nltk.word_tokenize(sentence)

    for word in tokens:
        if not word in english_punctuations:
            if not word in stopwords:
                word = stemmer.stem(word)
                print word

if __name__ == '__main__':
    main()

输出：

eight
o'clock
thursday
morn
arth
n't
feel
good
interest
book
stor