New submission from Antony Lee <anntzer....@gmail.com>:
Consider the following example, linewrapping 10^4 bytes in hex form to 128
characters per line, on Py 3.8.2 (Arch Linux repo package):
In [1]: import numpy as np, math
In [2]: data = np.random.randint(0, 256, (100, 100),
dtype=np.uint8).tobytes()
In [3]: %timeit data.hex("\n", -64)
123 µs ± 5.8 µs per loop (mean ± std. dev. of 7 runs, 10000 loops each)
In [4]: %timeit h = data.hex(); "\n".join([h[n * 128 : (n+1) * 128] for n
in range(math.ceil(len(h) / 128))])
45.4 µs ± 746 ns per loop (mean ± std. dev. of 7 runs, 10000 loops each)
In [5]: h = data.hex(); "\n".join([h[n * 128 : (n+1) * 128] for n in
range(math.ceil(len(h) / 128))]) == data.hex("\n", -64)
Out[5]: True
(the last line checks the validity of the code.)
It appears that a naive manual wrap is nearly 3x faster than the builtin
functionality.
----------
components: Library (Lib)
messages: 366678
nosy: Antony.Lee
priority: normal
severity: normal
status: open
title: bytes.hex(sep, bytes_per_sep) is many times slower than manually
inserting the separators
versions: Python 3.8
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue40313>
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