根据某些正则表达式断言条件提取多行

Question

我有一个很大的文本文件，我需要根据以下几行开头的特定条件提取某些数据块。如何使用 Python regex 包找到这些块并提取它们？

示例文件（source.txt）如下所示。

    .
    .
    .
    Request: 22:11:22
    Discription1: From the Client 1
    Discription2: requesting HTTP
    Version: 1.2
    Type: browsing
    Data: AAAA CFFFF FFF

    Answer: 33:22:44
    Discription1: From Server B
    Discription2: Respons HHTP
    Version: 1.1
    Type: browsing
    Data: kCmkc9AS 9as9 as99 as76d 8aS9d8 6ASDQWv sf

    Request: 31:24:53:33
    Discription1: From Client 2
       Discription2: requesting HTTP
        Version: 1.1

    Type: DASH
    Data: AAAA CFFFF FFF



    Answer: 41:24:33:33
    Discription1: From Server A
    Discription2: Response
    Version: 1.1
    Type: DASH
    Data:ask sef k5q3 WEB 54 fkl n5 qwe@#%@#SDG adkjwra;k4 kfk

    Request: 61:44:23:33
    Discription1: From Client 2
        Discription2: requesting HTTP

    Version: 1.1
       Type: DASH

    Data: AAAA CFFFF FFF
    Data Discription: From the Cleint VM2
    Answer: 71:25:33:33
      Discription1: From Server A
     Discription2: Response
        Version: 1.1
    Type: DASH

    Data:ask sef k5q3 WEB 54 fkl n5 qwe@#%@#SDG adkjwra;k4 kfk
    .
    .

我需要获取以“Request:”开头的块，其特征是：“version 1.1”和“Client 2”

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重要提示

1. 块的长度不同，所以它们不一样 信息，但它们具有相同的匹配特征。

2. 它们之间有很多空格和换行符。

3. 匹配的特征可能不完全出现在特定的行中 顺序。

4. 我需要将这些块捕获到以下“Answer”关键字。**

---

预期的输出是：

 Request: 31:24:53:33
    Discription1: From Client 2
    Discription2: requesting HTTP
    Version: 1.1
    Type: DASH
    Data: AAAA CFFFF FFF

    Request: 61:44:23:33
    Discription1: From Client 2
    Discription2: requesting HTTP
    Version: 1.1
    Type: DASH
    Data: AAAA CFFFF FFF
    Data Discription: From the Cleint VM2

Answer 1

您可以使用负前瞻来断言下一行的值：

^Message Request: .*(?:\r?\n(?!.* Client 2|Data:).*)*\r?\n.*Client 2.*(?:\r?\n(?!Version: 1\.1).*)*\r?\nVersion: 1\.1(?:\n(?!Data:).*)*\r?\nData: .*

说明

• ^行首
• Message Request: .* Match Message Request: 和其余的行
• (?:\r?\n(?!.* Client 2|Data:).*)*只要该行不包含Client 2或以Data开头就匹配：
• \r?\n.*Client 2.*匹配客户端2的行
• (?:\r?\n(?!Version: 1\.1).*)* 只要行不包含版本 1.1 就匹配
• \r?\nVersion: 1\.1匹配包含Version 1.1的行
• (?:\n(?!Data:).*)*只要该行不以Data开头就匹配：
• \r?\nData: .*匹配以Data开头的行：

Regex demo

例如使用re.M

import re
regex = r"^Message Request: .*(?:\r?\n(?!.* Client 2|Data:).*)*\r?\n.*Client 2.*(?:\r?\n(?!Version: 1\.1).*)*\r?\nVersion: 1\.1(?:\n(?!Data:).*)*\r?\nData: .*"

with open("source.txt", "r") as f:
    text1 = f.read()
print (re.findall(regex,text1, re.M))

结果

['Message Request: 31:24:53:33\nDiscription1: From Client 2\nDiscription2: requesting HTTP\nVersion: 1.1\nType: DASH\nData: AAAA CFFFF FFF', 'Message Request: 61:44:23:33\nDescription0:jdfj sdjd\nDiscription1: From Client 2\nDiscription2: requesting HTTP\nVersion: 1.1\nType: DASH\nData: AAAA CFFFF FFF']