Python Text Processing 简明教程
Python - Frequency Distribution
在文本处理期间,经常需要计算一个单词在一个文本主体中出现的频率。这可以通过应用 word_tokenize() 函数并将结果附加到一个列表来实现,以统计单词,如下面的程序所示。
from nltk.tokenize import word_tokenize
from nltk.corpus import gutenberg
sample = gutenberg.raw("blake-poems.txt")
token = word_tokenize(sample)
wlist = []
for i in range(50):
wlist.append(token[i])
wordfreq = [wlist.count(w) for w in wlist]
print("Pairs\n" + str(zip(token, wordfreq)))
当我们运行以上程序时,我们得到以下输出:
[([', 1), (Poems', 1), (by', 1), (William', 1), (Blake', 1), (1789', 1), (]', 1), (SONGS', 2), (OF', 3), (INNOCENCE', 2), (AND', 1), (OF', 3), (EXPERIENCE', 1), (and', 1), (THE', 1), (BOOK', 1), (of', 2), (THEL', 1), (SONGS', 2), (OF', 3), (INNOCENCE', 2), (INTRODUCTION', 1), (Piping', 2), (down', 1), (the', 1), (valleys', 1), (wild', 1), (,', 3), (Piping', 2), (songs', 1), (of', 2), (pleasant', 1), (glee', 1), (,', 3), (On', 1), (a', 2), (cloud', 1), (I', 1), (saw', 1), (a', 2), (child', 1), (,', 3), (And', 1), (he', 1), (laughing', 1), (said', 1), (to', 1), (me', 1), (:', 1), (``', 1)]
Conditional Frequency Distribution
条件频率分布用于我们在需要计算满足一组文本的特定条件的单词时。
import nltk
#from nltk.tokenize import word_tokenize
from nltk.corpus import brown
cfd = nltk.ConditionalFreqDist(
(genre, word)
for genre in brown.categories()
for word in brown.words(categories=genre))
categories = ['hobbies', 'romance','humor']
searchwords = [ 'may', 'might', 'must', 'will']
cfd.tabulate(conditions=categories, samples=searchwords)
当我们运行以上程序时,我们得到以下输出:
may might must will
hobbies 131 22 83 264
romance 11 51 45 43
humor 8 8 9 13