如何用Python的re模块提取指定短语后的首个数值？

问题场景 #

需要从给定句子中，提取短语**“tangible net worth”之后出现的首个数值**，具体示例如下：

示例句子 #

1. "A company must maintain a minimum tangible net worth of $100000000 and leverage ratio of 0.5"
2. "Minimum required tangible net worth the firm needs to maintain is $50000000"

预期目标 #

从两句中分别提取$100000000和$50000000，最终生成如下字典：

{
    "tangible net worth": "$100000000"
}

尝试过的无效正则 #

以下正则表达式均未得到预期结果：

re.search(r'net worth.*(\d+)', sent)
re.search(r'(net worth)(.*)(\d+)', sent)
re.search(r'(net worth)(.*)(\d?)', sent)
re.findall(r'tangible net worth (.*)?(\d* )', sent)
re.findall(r'tangible net worth (.*)?( \d* )', sent)
re.findall(r'tangible net worth (.*)?(\d)', sent)

解决方法 #

核心是用非贪婪匹配锁定短语到首个数值的区间，精准捕获目标数值。

有效正则表达式 #

使用re.search搭配以下正则：

r'tangible net worth.*?(\$\d+)'

• tangible net worth：精准匹配目标短语
• .*?：非贪婪匹配任意字符，确保只取到首个数值前的内容，不会跳过目标去匹配后面的数值
• (\$\d+)：捕获以$开头、后跟连续数字的数值（若需要兼容小数，可改为(\$\d+\.?\d*)）

完整Python代码 #

import re

# 待处理的句子列表
sentences = [
    "A company must maintain a minimum tangible net worth of $100000000 and leverage ratio of 0.5",
    "Minimum required tangible net worth the firm needs to maintain is $50000000"
]
target_phrase = "tangible net worth"
result = {}

for sent in sentences:
    match = re.search(r'tangible net worth.*?(\$\d+)', sent)
    if match:
        # 若要收集所有句子的结果，可改为列表存储
        result[target_phrase] = match.group(1)

print(result)

补充说明 #

• 如果句子中短语的大小写不固定，可添加re.IGNORECASE忽略大小写：re.search(r'tangible net worth.*?(\$\d+)', sent, re.IGNORECASE)
• 若数值格式多样（比如不带$、带逗号分隔如$100,000），可调整捕获组为([$]?\d[,\d]*)来适配

内容的提问来源于stack exchange，提问作者Ruchit