Python Tutorial: Automate Parsing and Renaming of Multiple Files

A practical Python script can fix messy, alphabetically sorted video filenames by renaming hundreds of files so they play in the intended numeric order on a phone playlist. The core issue is that downloaded course videos use a title-first naming pattern (title + dash + course name + number), which breaks ordering when devices sort strings alphabetically. The solution is to parse each filename, extract the embedded sequence number, and rebuild a new filename that starts with that number—optionally zero-padded—so “1, 2, 3 … 10” sorts correctly.

The workflow starts by using Python’s `os` module to work directly with the filesystem. The script changes into the folder containing the video files (`os.chdir(...)`), verifies the working directory with `os.getcwd()`, and lists the directory contents (`os.listdir(...)`) to confirm the filenames being processed. From there, each filename is split into its base name and extension using `os.path.splitext`, producing two parts: the name without the file type and the extension itself.

Next comes the parsing logic. The base filename is split on hyphens, yielding three components: the title, the course name, and the numeric sequence token. Those pieces are assigned to variables (e.g., `f_title`, `f_course`, `f_num`) and then recombined using a formatted string. The initial rebuild places the number first, followed by the course name and title, and finally the extension. Minor formatting issues—like stray spaces before the extension—are corrected with `.strip()`.

Two refinements address ordering and personal preference. First, the number token includes an unwanted leading character (a number sign), so the script slices the string to drop the first character (using `f_num[1:]`). Second, plain numeric strings cause “10” to sort near “1” because sorting is character-based. To prevent that, the script zero-pads single-digit numbers with `zfill(2)`, turning “1” into “01” and “2” into “02,” while leaving “10” unchanged. After that, the course name can be removed entirely from the new filename, leaving a cleaner format that still sorts correctly.

Finally, the script performs the rename operation inside a loop. For each original filename, it computes `new_name` and calls `os.rename(original_file, new_name)`. Running it once updates the entire directory, eliminating the tedium and error risk of manual renaming. The broader takeaway is that small, targeted scripts—built step by step with validation prints—can automate repetitive file-management tasks reliably and can be reused when similar naming problems show up again.