Python Tutorial: Zip Files - Creating and Extracting Zip Archives

Python can create, compress, and extract ZIP archives using the standard library’s `zipfile` module, and it can also handle archive workflows end-to-end inside automation scripts—downloading archives over the internet, saving them locally, and unpacking their contents. The core takeaway is that ZIP handling in Python is straightforward: open a ZIP for writing, add files with `write()`, then close it (preferably via a context manager). For extraction, open the archive in read mode, inspect contents with `namelist()`, and extract everything with `extractall()` or a single file with `extract()`.

The tutorial starts with local files to build intuition. A text file (`test.txt`) and an image (`thumbnail.png`) are added to a new archive named `files.zip` by opening `zipfile.ZipFile(..., 'w')` and calling `my_zip.write()` for each file. After running the script, the archive appears in the working directory and can be extracted by the operating system to confirm the contents. The workflow is then improved by switching from manual `close()` calls to a context manager (`with zipfile.ZipFile(...) as my_zip:`), which automatically handles closing even if errors occur.

Compression is addressed next. By default, the ZIP created by `zipfile` isn’t necessarily compressed in a way that’s noticeable for small archives. To control compression, the script passes `compression=zipfile.ZIP_DEFLATED` when opening the archive for writing. The same archive can then be read back: change the mode from `'w'` to `'r'`, list members with `my_zip.namelist()`, and extract with `my_zip.extractall('files')`. The tutorial also demonstrates selective extraction—extracting only `thumbnail.png` from a ZIP that contains multiple files.

A second approach uses `shutil`, which simplifies archiving for whole directories. With `shutil.make_archive(base_name, format, root_dir=...)`, the script creates a ZIP from an entire folder in a single call (e.g., producing `another.zip` from the `files` directory). Extraction is equally simple using `shutil.unpack_archive(archive_path, extract_dir)`. `shutil` also supports other archive formats by changing the `format` argument, including `tar`, `gztar` (producing `.tar.gz`), `bztar`, and `xztar`.

Finally, the tutorial moves from local archives to downloading ZIP files online. It uses `requests` to fetch a ZIP file from a URL, writes the response bytes to disk in binary mode, then opens the saved file with `zipfile.ZipFile` to print `namelist()` and (optionally) extract. A hiccup occurs with the Stack Overflow 2019 download link, producing a “bad zip file / file is not a zip file” error, so the tutorial switches to a GitHub repository ZIP download as a working fallback to demonstrate the same pipeline successfully.

Overall, the practical value is automation: scripts can fetch archives, verify their contents, and extract data without manual clicking—ideal for repeatable data ingestion tasks like downloading datasets and preparing them for analysis.