来自pandas专栏的Ngrams

Question

我有一个pandas数据框架，包含以下各列：

第1列

['if', 'you', 'think', 'she', "'s", 'cute', 'now', ',', 'you', 'should', 'have', 'see', 'her', 'a', 'couple', 'of', 'year', 'ago', '.']
['uh', ',', 'yeah', '.', 'just', 'a', 'fax', '.']

第2列

if you think she 's cute now , you should have see her a couple of year ago .
uh , yeah . just a fax .

等。

我的目标是计算数据帧的二元、三元、四元(具体地说，列2，它已经进行了词条分类)。

我尝试了以下几种方法：

import nltk
from nltk import bigrams
from nltk import trigrams

trig = trigrams(df ["Column2"])
print (trig)

但是，我有以下错误

<generator object trigrams at 0x0000013C757F1C48>

我的最终目标是能够打印出最上面的X bi gram，trigram等。

Answer 1

首先对所有三元组使用列表理解和split和flatten：

df = pd.DataFrame({'Column2':["if you think she cute now you if uh yeah just",
                              'you think she uh yeah just a fax']}) 

from nltk import trigrams

L = [x for x in df['Column2'] for x in trigrams(x.split())]
print (L)
[('if', 'you', 'think'), ('you', 'think', 'she'), ('think', 'she', 'cute'), 
 ('she', 'cute', 'now'), ('cute', 'now', 'you'), ('now', 'you', 'if'), 
 ('you', 'if', 'uh'), ('if', 'uh', 'yeah'), ('uh', 'yeah', 'just'), 
 ('you', 'think', 'she'), ('think', 'she', 'uh'), ('she', 'uh', 'yeah'),
 ('uh', 'yeah', 'just'), ('yeah', 'just', 'a'), ('just', 'a', 'fax')]

然后通过collections.Counter计算元组

from collections import Counter
c = Counter(L)
print (c)
Counter({('you', 'think', 'she'): 2, ('uh', 'yeah', 'just'): 2, ('if', 'you', 'think'): 1,
         ('think', 'she', 'cute'): 1, ('she', 'cute', 'now'): 1, ('cute', 'now', 'you'): 1,
         ('now', 'you', 'if'): 1, ('you', 'if', 'uh'): 1, ('if', 'uh', 'yeah'): 1, 
         ('think', 'she', 'uh'): 1, ('she', 'uh', 'yeah'): 1, 
         ('yeah', 'just', 'a'): 1, ('just', 'a', 'fax'): 1})

对于顶值，请使用collections.Counter.most_common：

top = c.most_common(5)
print (top)
[(('you', 'think', 'she'), 2), (('uh', 'yeah', 'just'), 2), 
 (('if', 'you', 'think'), 1), (('think', 'she', 'cute'), 1),
 (('she', 'cute', 'now'), 1)]