Python正则提取pandas DataFrame中{}内数值无分组报错求助

问题原因 #

pandas的str.extractall()方法要求正则表达式必须包含至少一个捕获组（即用小括号包裹的匹配片段），你修改后的正则只有前后断言规则，没有给要提取的内容加捕获括号，所以触发了「pattern contain no group」报错。

修复后可运行代码 #

import pandas as pd

# 测试用DataFrame
df = pd.DataFrame([["{1} | | Had a Greeter welcome clients {1.0}     | | Take measures to ensure a safe and organized distribution {1.000}         | | Protected confidentiality of clients (on social media, pictures, in conversation, own congregation members receiving assistance, etc.)",
                    "{1.00}  | | Chairs for clients to sit in while waiting {1.0000}     | | Take measures to ensure a safe and organized distribution"],
                   ["{1  } | Financial literacy/budgeting {1   } | | Monetary/Bill Support {1}    | | Mental Health Services/Counseling",
                    "{1}| | Clothing Assistance {1       }  | | Healthcare {1}    | | Mental Health Services/Counseling {1}     | | Spiritual Support {1}      | | Job Skills Training"]
                    ] , columns = ['CF1', 'CF2'])

# 核心逻辑修正版
result = (
    df.stack()
    .str.extractall(r'(?<=\{)([\d+\.\ ]+)(?=\})') # 给目标匹配段加捕获括号
    [0]
    .str.strip() # 清除匹配到的前后冗余空格
    .astype(float) # 先转浮点数兼容小数点格式
    .astype(int) # 再转整数求和
    .groupby(level=[0,1])
    .sum()
    .unstack()
)

运行后输出结果：

内容的提问来源于stack exchange，提问作者BeginnerProgrammer