python / expert
Snippet
Zero-Copy Slicing with memoryview
The memoryview object allows Python code to access the internal data of an object that supports the buffer protocol (like bytearray) without copying. Slicing a memoryview returns a new memoryview that shares the same underlying buffer, enabling extremely efficient memory manipulation for large datasets.
snippet.py
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data = bytearray(b'X' * 100_000_000)mv = memoryview(data)chunk = mv[1000:2000]# No data is copied herechunk[0] = ord('Y')print(data[1000]) # Outputs: 89 ('Y')
Breakdown
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mv = memoryview(data)
Creates a view of the underlying memory buffer of the bytearray.
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chunk = mv[1000:2000]
Creates a slice of the view; this is a 'view of a view' with zero copying.
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chunk[0] = ord('Y')
Modifying the slice directly updates the original bytearray data.