Python提取含1-6位数字（首尾可带字符）的行及ETEXT NO相关信息

Let's break down your problems one by one, starting with why your regex didn't work and then fixing both requirements.

Why Your Regex Failed #

Your pattern ^[a-zA-Z]\d{1,6}$ is way too restrictive:

• ^ and $ anchor the match to the start and end of the line, so it only matches lines that start with a single letter, followed by 1-6 digits, and nothing else.
• This doesn't account for lines with other characters before/after the number, or numbers that aren't immediately after a letter.

1. Extract Lines Containing 1-6 Digit Numbers #

If you want lines that contain any 1-6 digit sequence (even if surrounded by other characters), use this regex to match such lines:

.*\d{1,6}.*

• .* matches any characters (including none) before the digits.
• \d{1,6} matches 1 to 6 digits.
• .* matches any characters after the digits.

If you want to ensure you're matching standalone 1-6 digit numbers (not part of a longer number like 1234567), use negative lookarounds to exclude digits before/after:

.*(?<!\d)\d{1,6}(?!\d).*

• (?<!\d): Ensures no digit comes right before the sequence.
• (?!\d): Ensures no digit comes right after the sequence.

Example Implementation (Python) #

Here's how to extract these lines using Python:

import re

# Choose one pattern below
pattern = r".*(?<!\d)\d{1,6}(?!\d).*"  # For standalone 1-6 digit numbers
# pattern = r".*\d{1,6}.*"  # For any line with 1-6 digits (even part of longer numbers)

with open("your_file.txt", "r") as f:
    for line in f:
        cleaned_line = line.strip()
        if re.match(pattern, cleaned_line):
            print(cleaned_line)

2. Look Up Entries by ETEXT NO #

Assuming your file has entries structured like this (common for ETEXT-style files):

ETEXT NO: 1234
Title: The Adventures of Tom Sawyer
Author: Mark Twain
...

We can parse the file into a searchable dictionary where keys are ETEXT NOs, and values hold the title and author. Then you can easily look up entries.

Example Python Code #

import re

def parse_etext_entries(file_path):
    etext_database = {}
    current_entry = {}
    
    with open(file_path, "r") as f:
        for line in f:
            cleaned_line = line.strip()
            # Match ETEXT NO line
            etext_match = re.match(r"ETEXT NO:\s*(\d+)", cleaned_line)
            if etext_match:
                # Save previous entry if it exists
                if current_entry:
                    etext_database[current_entry["etext_no"]] = current_entry
                # Start a new entry
                current_entry = {"etext_no": etext_match.group(1)}
            # Match Title line
            title_match = re.match(r"Title:\s*(.*)", cleaned_line)
            if title_match:
                current_entry["title"] = title_match.group(1)
            # Match Author line
            author_match = re.match(r"Author:\s*(.*)", cleaned_line)
            if author_match:
                current_entry["author"] = author_match.group(1)
        # Add the final entry to the database
        if current_entry:
            etext_database[current_entry["etext_no"]] = current_entry
    
    return etext_database

# Usage example
entries = parse_etext_entries("your_file.txt")

# Look up a specific ETEXT NO
target_no = "1234"
if target_no in entries:
    entry = entries[target_no]
    print(f"ETEXT NO: {entry['etext_no']}")
    print(f"Title: {entry['title']}")
    print(f"Author: {entry['author']}")
else:
    print(f"No entry found for ETEXT NO {target_no}")

Quick Notes: #

• Adjust the regex patterns for ETEXT NO:, Title:, and Author: if your file uses different formatting (e.g., all caps, colons in different places).
• If your entries are separated by blank lines, add a check to reset current_entry when a blank line is encountered.

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