iabhi4 opened a new issue, #46589:
URL: https://github.com/apache/arrow/issues/46589
### Describe the bug, including details regarding any error messages,
version, and platform.
### Description
The `utf8_is_digit` kernel in `pyarrow.compute` does not fully replicate
Python's `str.isdigit()` behavior, especially with certain Unicode digit
characters.
For example, the character `'³'` (U+00B3 SUPERSCRIPT THREE) returns `True`
with Python’s `str.isdigit()` but returns `False` when passed to
`pyarrow.compute.utf8_is_digit`.
This divergence leads to downstream inconsistencies, particularly in pandas
when using `StringDtype(storage="pyarrow")`.
---
### Reproduction
```python
import pyarrow as pa
import pyarrow.compute as pc
arr = pa.array(['3', '٣', '५', '１２３', '³'])
print(pc.utf8_is_digit(arr).to_pylist())
```
**Output:**
```
[True, True, True, True, False] # <-- '³' incorrectly returns False
```
**Expected Output (matches `str.isdigit()`):**
```
[True, True, True, True, True]
```
---
### Notes
- The issue seems to stem from the implementation of
`IsDigitUnicode::PredicateCharacterAll` not including characters in the Unicode
"No" (Number, Other) category, such as superscript digits (`³`, `²`, etc.).
- Python's behavior can be verified as:
```python
print("³".isdigit()) # True
```
---
### Impact
This affects pandas string operations like `.str.isdigit()` when using
`pyarrow` storage. Python string-based behavior passes, but pyarrow-based
behavior fails for characters like `'³'`.
---
### System Info
Tested with:
- PyArrow 20.0.0 (pip-installed)
- Pyarrow `main` 0.1.dev17578+g218c886
- Python 3.12
- Debian-based Linux (Ubuntu)
### Component(s)
Python
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