Скачать или смотреть How to Use Python to Add Lines to a Text File Based on Specific Content

Learn how to add lines to a text file in Python when a specific line is found, using regex for effective parsing.
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This video is based on the question https://stackoverflow.com/q/64585208/ asked by the user 'Henry Nguyen' ( https://stackoverflow.com/u/14475568/ ) and on the answer https://stackoverflow.com/a/64585426/ provided by the user 'arulmr' ( https://stackoverflow.com/u/1095090/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Use Python to Add Lines to a Text File Based on Specific Content

Sometimes, when working with text files, you might need to modify the content based on specific criteria. If you're a Python enthusiast or developer facing a challenge while trying to add lines to a text file when a specific line is found, you've come to the right place!

The Problem: Adding Lines in a Text File

You may have a situation where you want to analyze logs or records stored in a text file. In a specific example, you want to process timestamps and stations recorded in the file, and insert a new line following each timestamp before any station appearances.

Here's an example of the current text file (let's call it text.txt):

[[See Video to Reveal this Text or Code Snippet]]

You want the resulting file (let's call it text2.txt) to look like this:

[[See Video to Reveal this Text or Code Snippet]]

The Solution: Correcting the Python Code

Let's walk through how to correct your Python script to achieve this functionality. The initial approach you provided has some issues, namely an indentation error and the way conditions are structured. We'll fix that using regular expressions for improved line matching.

Here's the revised code:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Code Fixes

Regex Pattern: We defined a regex pattern that accurately captures the date format.

Loop Through File: We open the input file for reading and output file for writing.

Date Extraction: We assign the matched date to the date variable.

Condition for Stations: We ensure that when a line starting with "station" is encountered, the Time: line is appropriately prepended.

Writing to Output: Each line, whether modified or not, is written to the new text file.

Conclusion

With this refined code, you should be able to meet your goal of adding corresponding timestamps before the stations in your text file. This process not only simplifies your log parsing but also makes your output more informative.

Feel free to reach out if you have further questions or need assistance with similar coding challenges!