Extract Specific Sections from a Text File Using Python Regex – Step‑by‑Step Guide

Introduction

Hello, I am PiPi. A fellow member of a Python community asked how to process a text file to extract specific sections using Python.

The original requirement is illustrated in the following screenshots:

Implementation Process

First, a straightforward script using a regular expression was written:

import re
with open('西游记.txt', 'r', encoding='utf-8') as f:
    text = f.read()
regex = re.compile(r'.*?《》(.*?)《》.*?', re.S)
result = re.findall(regex, text)
print(len(list(result)))
for item in result:
    print(item)

The script produced the output shown below:

A reviewer noticed a problem and suggested improvements. The revised code is:

import re

with open('西游记.txt', 'r+', encoding='utf-8') as f:
    txt = f.read()

rex1 = r'《》目录 (.*?)


'
rex2 = r'《》目录 (第一百回.*?《西游记》至此终。)'
result = re.findall(rex1, txt, re.S)
temp = re.findall(rex2, txt, re.S)
result += temp
# print(len(result))
for item in result:
    print(item)

Running the improved script yields the following result:

Summary

The problem was solved by applying regular expressions to locate and extract the required text fragments from the source file. The article demonstrates the initial approach, identifies its shortcomings, and presents a refined solution that successfully meets the user's needs.