I’m still a bit new to Python but not new to regex. I’m using Python 3.11 on Windows 10. I want to check if a filename does not end with .xlsx or .csv (does not match '(xlsx|csv)$') then print an error. But regex is not working as expected. I must be missing something specific to Python. >>> impor…

re.match tries to match the whole string, not just a piece of it. You could use .*(xlsx|csv)$ to match the prefix or you could use re.search to search the string. edit: As you found, match and search are different.

Thank you. Does re.search look for a match starting from the first character, or does it only return the first matching string?

I actually made a mistake. match tries to match the beginning of the string, but doesn’t need to match the whole thing. that’s re.fullmatch. The documentation covers all of this. [image] Chuck R.: Thank you. Does re.search look for a match starting from the first character, or does it only retu…

Reference: [Daryl Spitzer] What is the difference between re.search and re.match? python, regex, search, match asked by Daryl Spitzer on 12:51AM - 08 Oct 08 UTC [image] Rationale for re.search, re.match, and…

[image] Chuck R.: What am I doing wrong here? You are not including the “.” In the pattern so it will match foo.notcsv as well. Personally I would use filename.lower().endswith((“.csv”, “.xlsx”)) in the case.

[image] Chuck R.: I want to check if a filename does not end with .xlsx or .csv It’s often helpful to handle file paths as path objects instead of working with raw strings. That can help save you from re-inventing the wheel every time you need to do a basic path parsing or manipulation, and c…

[image] Brian Schubert: It’s often helpful to handle file paths as path objects instead of working with raw strings Thanks, I’m still learning and memorizing many details about Python. I will take notes on this one.

[image] Barry Scott: Personally I would use filename.lower().endswith((“.csv”, “.xlsx”)) in the case. If .endswith() takes a tuple as a parameter, should the tuple end with a comma like this? .endswith((".csv", ".xlsx",)) One of my Python tutorials said all tuples must end with a comma after…

[image] Chuck R.: If .endswith() takes a tuple as a parameter, should the tuple end with a comma like this? .endswith((".csv", ".xlsx",)) No, tuples are not required to end with a trailing comma. Trailing commas are only strictly necessary when creating a single-element tuples like (1,) (with…

[image] Brian Schubert: P.S. if you goal is to validate that a file is a CSV/Excel file, I’d recommend waiting until you actually read the file instead of trying to make that determination preemptively from the file name alone. There’s plenty of reasons why (for example) a valid CSV file might n…

Why is this regex not matching the filename?

Python Help

bschubert (Brian Schubert) May 16, 2024, 4:05pm 5

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