在NLP任务中，常需要分析单词的词性，借助nltk库的pos_tag方法可以较好地实现。

以下是一个例子：

import nltk

line = 'i love this world which was beloved by all the people here'

tokens = nltk.word_tokenize(line)

# ['i', 'love', 'this', 'world', 'which', 'was', 'beloved', 'by',

# 'all', 'the', 'people', 'here']

pos_tags = nltk.pos_tag(tokens)

# [('i', 'RB'), ('love', 'VBP'), ('this', 'DT'), ('world', 'NN'), ('which', 'WDT'),

# ('was', 'VBD'), ('beloved', 'VBN'), ('by', 'IN'), ('all', 'PDT'), ('the', 'DT'),

# ('people', 'NNS'), ('here', 'RB')]

for word,pos in pos_tags:

if (pos == 'NN' or pos == 'NNP' or pos == 'NNS' or pos == 'NNPS'):

print word,pos

# world NN

# people NNS

作为nltk的替代，TextBlob库能够更进一步进行词组划分，例如“computer science”会被当做一个单词，而非"computer"和"science"

from textblob import TextBlob

txt = """Natural language processing (NLP) is a field of computer science, artificial intelligence, and computational linguistics concerned with the inter

actions between computers and human (natural) languages."""

blob = TextBlob(txt)

print(blob.noun_phrases)

# [u'natural language processing', 'nlp', u'computer science', u'artificial intelligence', u'computational linguistics']

更多例子请参考nltk官方教科书第五章

其中pos_tag分析出来的词性含义按照宾夕法尼亚大学tag词性对照表

tag

含义

CC

Coordinating conjunction

CD

Cardinal number

DT

Determiner

EX

Existential there

FW

Foreign word

IN

Preposition or subordinating conjunction

JJ

Adjective

JJR

Adjective, comparative

JJS

Adjective, superlative

LS

List item marker

MD

Modal

NN

Noun, singular or mass

NNS

Noun, plural

NNP

Proper noun, singular

NNPS

Proper noun, plural

PDT

Predeterminer

POS

Possessive ending

PRP

Personal pronoun

PRP$

Possessive pronoun

RB

Adverb

RBR

Adverb, comparative

RBS

Adverb, superlative

RP

Particle

SYM

Symbol

TO

to

UH

Interjection

VB

Verb, base form

VBD

Verb, past tense

VBG

Verb, gerund or present participle

VBN

Verb, past participle

VBP

Verb, non-3rd person singular present

VBZ

Verb, 3rd person singular present

WDT

Wh-determiner

WP

Wh-pronoun

WP$

Possessive wh-pronoun

WRB

Wh-adverb