计算字符串列表中单词的出现次数

Question

如何计算一个单词出现在字符串列表中的次数？

例如：

['This is a sentence', 'This is another sentence']

单词“句子”的结果是2

Answer 1

使用一个collections.Counter()对象并在空白处分割单词。您可能还希望小写单词，并删除标点符号：

from collections import Counter

counts = Counter()

for sentence in sequence_of_sentences:
    counts.update(word.strip('.,?!"\'').lower() for word in sentence.split())

或使用仅与单词字符匹配的正则表达式：

from collections import Counter
import re

counts = Counter()
words = re.compile(r'\w+')

for sentence in sequence_of_sentences:
    counts.update(words.findall(sentence.lower()))

现在，您有了一counts本包含每个单词计数的字典。

演示：

>>> sequence_of_sentences = ['This is a sentence', 'This is another sentence']
>>> from collections import Counter
>>> counts = Counter()
>>> for sentence in sequence_of_sentences:
...     counts.update(word.strip('.,?!"\'').lower() for word in sentence.split())
... 
>>> counts
Counter({'this': 2, 'is': 2, 'sentence': 2, 'a': 1, 'another': 1})
>>> counts['sentence']
2