Pablo Galindo Salgado <[email protected]> added the comment:
> That is a one-off cost for the __length_hint__ of the range object
> specifically.
Objects with a known length (lists, sets, tuples) would not have that overhead.
That seems incorrect. This is not unique of range objects as it affects also
objects with known lengths (like a list):
import perf
runner = perf.Runner()
runner.timeit("list_comp",
stmt="[x*2 for x in k]",
setup="k=list(range(10))")
Current master:
❯ ./python.exe ../check.py -n 10
.....................
list_comp: Mean +- std dev: 3.82 us +- 0.13 us
PR 12718:
❯ ./python.exe ../check.py -n 10
.....................
list_comp: Mean +- std dev: 4.38 us +- 0.16 us
Check also my other benchmark with a list iterator ( iter(list(range(10))) ) or
this one with a generator comp:
import perf
runner = perf.Runner()
runner.timeit("list_comp",
stmt="[x*2 for x in it]",
setup="k=list(range(10));it=(x for x in k)")
Current master:
❯ ./python.exe ../check.py -n 10
.....................
list_comp: Mean +- std dev: 967 ns +- 27 ns
PR 12718:
❯ ./python.exe ../check.py -n 10
.....................
list_comp: Mean +- std dev: 1.22 us +- 0.04 us
----------
nosy: +pablogsal
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<https://bugs.python.org/issue36551>
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