显示空列表时出现正则表达式错误，尽管字符串中存在该模式

Question

import re
lyrics = '''Twelve drummers drumming, eleven pipers piping
Ten lords a leaping, nine ladies dancing, eight maids a milking
Seven swans a swimming, six geese a laying, five gold rings
Four calling birds, three French hens
Two turtle doves and a partridge in a pear tree
'''
xmasReExp = re.compile(r'\d+\s\w+')
print(xmasReExp.findall(lyrics))

Answer 1

结果是正确的，即空列表\d表示数字，而lyrics中没有匹配的模式

Answer 2

如果我理解正确，您希望查找文本lyrics中用单词书写的数字。由于正则表达式无法理解一个单词，因此需要首先解决这个问题。为此，您可以：

• 创建从单词到数字的映射
• 在文本上应用映射
• 在新文本上使用regex，以获取数字

样本

import re

# mapping
word_digit_map = {
    "one": 1,
    "two": 2,
    "three": 3,
    "four": 4,
    "five": 5,
    "six": 6,
    "seven": 7,
    "eight": 8,
    "nine": 9,
    "ten": 10,
    "eleven": 11,
    "twelve": 12,
}

lyrics = '''Twelve drummers drumming, eleven pipers piping
Ten lords a leaping, nine ladies dancing, eight maids a milking
Seven swans a swimming, six geese a laying, five gold rings
Four calling birds, three French hens
Two turtle doves and a partridge in a pear tree
'''

# apply mapping
for word in word_digit_map.keys():
    lyrics = lyrics.lower().replace(word, str(word_digit_map[word]))

# Use regex
xmasReExp = re.compile(r'\d+')
print(xmasReExp.findall(lyrics))

Out

['12', '11', '10', '9', '8', '7', '6', '5', '4', '3', '2']