fix(transliterate): romanize royin words containing ฤ - #1473
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romanize(..., engine="royin") raised IndexError on words containing ฤ (U+0E24), e.g. ฤดู, ฤก, ฤทธิ์. _romanize() built its consonant list with _RE_CONSONANT, which matches only thai_consonants and so excludes ฤ, while _replace_consonants() treats every key of _CONSONANTS - including ฤ - as a consonant and advances its index for each one. The two went out of sync and the index ran past the end of the list. The consonant list is now built with the same membership test the loop uses, so ฤ is romanized through its existing _CONSONANTS entry. Adds RU_TESTS and test_romanize_royin_ru to tests/core/test_transliterate.py. Closes PyThaiNLP#1444
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Pull request overview
Fixes a bug in the royin RTGS romanization engine where words containing ฤ (U+0E24) could crash with an IndexError, and adds regression coverage to ensure these words romanize correctly going forward.
Changes:
- Build the consonant list in
_romanize()using_CONSONANTSkey membership to keep indexing consistent with_replace_consonants(). - Add regression tests for representative ฤ-containing words and their expected romanizations.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.
| File | Description |
|---|---|
| pythainlp/transliterate/royin.py | Aligns consonant collection with _replace_consonants() behavior to prevent IndexError on ฤ words. |
| tests/core/test_transliterate.py | Adds regression tests for ฤ-containing words to validate correct royin romanization. |
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
wannaphong
approved these changes
Aug 3, 2026
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What do these changes do
Make
romanize(..., engine="royin")handle words containing ฤ (U+0E24) instead of raisingIndexError, and add a regression test for them.What was wrong
_romanize()built its consonant list with_RE_CONSONANT, which is compiled fromthai_consonantsand therefore does not match ฤ._replace_consonants(), however, treats every key of_CONSONANTS— which does include ฤ — as a consonant and advances its index for each one. On a word containing ฤ the index ran past the end of the list, soromanize("ฤดู", engine="royin")raisedIndexError: string index out of range.How this fixes it
The consonant list is now built with the same membership test the loop uses (
c in _CONSONANTS), keeping the two in sync and letting ฤ romanize through its existing_CONSONANTSentry. ฤก→rueok, ฤดู→rueadu, ฤทธิ์→rueot; words without ฤ are byte-identical to before, including ฤ words that did not crash (พฤษภาคม, อังกฤษ, พฤหัสบดี, นฤมล, ทฤษฎี).Fixes #1444
Your checklist for this pull request
test_romanize_royin_ruwas added totests/core/test_transliterate.pybeside the existing royin tests; it fails without the source fix (the reportedIndexError) and passes with it.tests/core/test_transliterate.pypasses in full, andruff checkis clean on both changed files.This change was prepared with AI assistance; the regression test was run locally and fails without the fix.