New submission from Sergey Fedoseev <fedoseev.ser...@gmail.com>:
Script for benchmarks:
NAME=list-slice.json
python -m perf timeit --name "l[len(l):] = reversed(l)" -l 1 -s "l = [None] *
1000000" "l[len(l):] = reversed(l)" --append $NAME
python -m perf timeit --name "l[len(l):] = l" -l 1 -s "l = [None] * 1000000"
"l[len(l):] = l" --append $NAME
python -m perf timeit --name "l[::-1] = l" -s "l = [None] * 1000000" "l[::-1] =
l" --append $NAME
python -m perf timeit --name "l[:] = l" -s "l = [None] * 1000000" "l[:] = l"
--append $NAME
python -m perf timeit --name "l[len(l)//2:] = l" -l 1 -s "l = [None] * 1000000"
"l[len(l)//2:] = l" --append $NAME
python -m perf timeit --name "l[:len(l)//2] = l" -l 1 -s "l = [None] * 1000000"
"l[:len(l)//2] = l" --append $NAME
python -m perf timeit --name "l[len(l)//4:len(l)*3//4] = l" -l 1 -s "l = [None]
* 1000000" "l[len(l)//4:len(l)*3//4] = l" --append $NAME
Results table:
+------------------------------+-------------------+------------------------------------+
| Benchmark | list-slice-master | list-slice
|
+==============================+===================+====================================+
| l[len(l):] = reversed(l) | 8.44 ms | 5.18 ms: 1.63x faster
(-39%) |
+------------------------------+-------------------+------------------------------------+
| l[len(l):] = l | 7.88 ms | 3.37 ms: 2.34x faster
(-57%) |
+------------------------------+-------------------+------------------------------------+
| l[::-1] = l | 10.4 ms | 582 us: 17.85x faster
(-94%) |
+------------------------------+-------------------+------------------------------------+
| l[:] = l | 10.6 ms | 86.1 ns: 123128.46x faster
(-100%) |
+------------------------------+-------------------+------------------------------------+
| l[len(l)//2:] = l | 11.1 ms | 2.08 ms: 5.33x faster
(-81%) |
+------------------------------+-------------------+------------------------------------+
| l[:len(l)//2] = l | 11.5 ms | 1.76 ms: 6.53x faster
(-85%) |
+------------------------------+-------------------+------------------------------------+
| l[len(l)//4:len(l)*3//4] = l | 11.3 ms | 2.27 ms: 4.98x faster
(-80%) |
+------------------------------+-------------------+------------------------------------+
----------
components: Interpreter Core
messages: 321908
nosy: sir-sigurd
priority: normal
severity: normal
status: open
title: performance of some list slice assignment can be improved
type: performance
_______________________________________
Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue34152>
_______________________________________
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