Fix: Replace polyglot with NLTK alternatives to resolve HTTP 403 error

[jalajthanaki]

Fix: Replace polyglot with NLTK alternatives to resolve HTTP 403 error

Summary

This PR resolves the HTTP 403 error that occurs when running ch3/3_1_wordsteam.py by replacing the polyglot library dependency with NLTK-based alternatives. The polyglot download server (http://polyglot.cs.stonybrook.edu/~polyglot/) is permanently down or misconfigured, returning 403 Forbidden errors when attempting to download morpheme analyzer resources.

Changes made:

• Removed polyglot imports and dependency on polyglot.text.Word
• Replaced polyglot_stem() function with nltk_alternative_stem() using NLTK's Porter, Lancaster, and Snowball stemmers
• Updated all print statements from Python 2 to Python 3 syntax (added parentheses)
• Added comparison table showing output from three different NLTK stemmers

Root cause: The polyglot library's server infrastructure is no longer accessible, causing runtime failures. This is a known issue affecting many users (see GitHub issues #204, #282, etc.).

Review & Testing Checklist for Human

• Run the script and verify it executes without errors: python3 ch3/3_1_wordsteam.py
• Review educational impact: This code is from Chapter 3 of your "Python Natural Language Processing" book. Consider whether removing polyglot entirely (vs. making it optional) preserves the intended learning objectives about morphological analysis.
• Verify semantic equivalence: Note that NLTK stemming is not exactly equivalent to polyglot's morpheme analysis. Stemmers reduce words to root forms, while morpheme analyzers break words into meaningful units. The output will be similar but conceptually different.
• Confirm Python 3 migration is acceptable: This change breaks Python 2 compatibility. If readers of the book are still using Python 2, they'll need updated instructions.
• Test with NLTK installation: Ensure nltk is included in requirements/setup instructions: pip install nltk

Notes

• The script now demonstrates three NLTK stemmers (Porter, Lancaster, Snowball) providing educational value through comparison
• Original error occurred because polyglot tries to download resources on first use, but the server returns 403
• Alternative solution would be to make polyglot optional with try/except, but given the library appears unmaintained (last release 16.7.4, years old), complete replacement is more sustainable

Session URL: https://app.devin.ai/sessions/c36fa9675f274b57b1138a74ecbd8a7f
Requested by: jalajthanaki@gmail.com (@jalajthanaki)

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