seniorNumPy
How does NumPy optimize chained indexing performance?
Updated May 17, 2026
Short answer
Chained indexing may trigger multiple intermediate views or copies, reducing performance.
Deep explanation
Expressions like arr[1:][2:] may create intermediate arrays depending on stride layout. Each step can produce a new view or copy, increasing memory overhead. NumPy does not always fuse chained indexing operations, which can lead to inefficiencies in large datasets.
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