seniorNumPy
How does NumPy handle internal indexing performance differences between integer and boolean arrays?
Updated May 17, 2026
Short answer
Integer indexing is direct and faster, while boolean indexing requires mask evaluation and gathering.
Deep explanation
Integer indexing accesses memory directly using computed offsets, making it efficient. Boolean indexing first evaluates a mask array and then gathers elements, requiring additional passes over memory. This makes boolean indexing more flexible but slower.
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