[Compatibility Issue] np.bool removed in NumPy 1.24 — use bool instead

[xyf5432]

Affected File

causallib/preprocessing/filters.py:255

Current Code

is_removed = np.zeros(X.shape[1], dtype=np.bool)

Root Cause

np.bool was deprecated in NumPy 1.20 and fully removed in NumPy 1.24 (2022-12). In NumPy >= 1.24, using np.bool raises:

AttributeError: module 'numpy' has no attribute 'bool'

np.bool was an alias for Python's built-in bool.

Impact

• Severity: High — hard crash at runtime on NumPy >= 1.24
• Affects the correlation-based feature filtering in preprocessing/filters.py

Solution

# Before:
is_removed = np.zeros(X.shape[1], dtype=np.bool)

# After:
is_removed = np.zeros(X.shape[1], dtype=bool)

Python's built-in bool is the canonical replacement. np.bool_ can also be used if NumPy scalar type is explicitly required.

References

• NumPy 1.24 release notes — np.bool removed
• NumPy 1.20 deprecation: https://numpy.org/doc/stable/release/1.20.0-notes.html#deprecations
• Similar fix in another downstream project: ultralytics#22930