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Optimize naturalsize algorithm by using math.log #253

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hugovk merged 2 commits into from
May 23, 2025
+5 −11
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Optimize naturalsize algorithm by using math.log #253

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Optimize naturalsize algorithm by using math.log
Zaczero May 23, 2025
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pre-commit-ci[bot] May 23, 2025
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16 changes: 5 additions & 11 deletions src/humanize/filesize.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,8 @@

from __future__ import annotations

from math import log

suffixes = {
"decimal": (
" kB",
Expand Down Expand Up @@ -83,11 +85,7 @@ def naturalsize(
suffix = suffixes["decimal"]

base = 1024 if (gnu or binary) else 1000
if isinstance(value, str):
bytes_ = float(value)
else:
bytes_ = value

bytes_ = float(value)
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@Zaczero Zaczero May 23, 2025

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It's also faster to simply cast to float rather than do isinstance call.

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@hugovk hugovk May 23, 2025 •
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Yep:

❯ python --version
Python 3.14.0b1

❯ python -m timeit -s "value = 123.456" "bytes_ = float(value) if isinstance(value, str) else value"
10000000 loops, best of 5: 24.9 nsec per loop

❯ python -m timeit -s "value = 123.456" "bytes_ = float(value)"
20000000 loops, best of 5: 13.7 nsec per loop

❯ python -m timeit -s "value = '123.456'" "bytes_ = float(value) if isinstance(value, str) else value"
5000000 loops, best of 5: 47.7 nsec per loop

❯ python -m timeit -s "value = '123.456'" "bytes_ = float(value)"
10000000 loops, best of 5: 36.2 nsec per loop

Although in isolation this change would fail:

AssertionError: assert '1000.0 ZB' == '1.0 YB'

abs_bytes = abs(bytes_)

if abs_bytes == 1 and not gnu:
Expand All @@ -96,10 +94,6 @@ def naturalsize(
if abs_bytes < base:
return f"{int(bytes_)}B" if gnu else f"{int(bytes_)} Bytes"

for i, s in enumerate(suffix, 2):
unit = base**i
if abs_bytes < unit:
break

ret: str = format % (base * (bytes_ / unit)) + s
exp = int(min(log(abs_bytes, base), len(suffix)))
ret: str = format % (bytes_ / (base**exp)) + suffix[exp - 1]
return ret
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