Speed-up statistics.fmean()

[rhettinger]

BPO	37158
Nosy	@rhettinger, @stevendaprano
PRs	bpo-37158: Simplify and speed-up statistics.fmean() #13832 [3.8] bpo-37158: Simplify and speed-up statistics.fmean() (GH-13832) #13843

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/stevendaprano'
closed_at = <Date 2019-06-05.16:49:57.163>
created_at = <Date 2019-06-05.05:24:04.274>
labels = ['3.8', 'library', '3.9', 'performance']
title = 'Speed-up statistics.fmean()'
updated_at = <Date 2019-06-05.16:49:57.162>
user = 'https://github.com/rhettinger'

bugs.python.org fields:

activity = <Date 2019-06-05.16:49:57.162>
actor = 'rhettinger'
assignee = 'steven.daprano'
closed = True
closed_date = <Date 2019-06-05.16:49:57.163>
closer = 'rhettinger'
components = ['Library (Lib)']
creation = <Date 2019-06-05.05:24:04.274>
creator = 'rhettinger'
dependencies = []
files = []
hgrepos = []
issue_num = 37158
keywords = ['patch']
message_count = 5.0
messages = ['344670', '344726', '344733', '344746', '344747']
nosy_count = 2.0
nosy_names = ['rhettinger', 'steven.daprano']
pr_nums = ['13832', '13843']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'performance'
url = 'https://bugs.python.org/issue37158'
versions = ['Python 3.8', 'Python 3.9']

[rhettinger]

fmean() can be sped-up by converting count() from a function to a generator and by using enumerate() to do the counting.

-- Baseline ---

$ ./python.exe -m timeit -r11 -s 'from statistics import fmean' -s 'data=list(map(float, range(1000)))' 'fmean(iter(data))'
2000 loops, best of 11: 108 usec per loop

-- Patched --
$ ./python.exe -m timeit -r11 -s 'from statistics import fmean' -s 'data=list(map(float, range(1000)))' 'fmean(iter(data))'
5000 loops, best of 11: 73.1 usec per loop

[rhettinger]

New changeset 6c01ebc by Raymond Hettinger in branch 'master':
bpo-37158: Simplify and speed-up statistics.fmean() (GH-13832)
6c01ebc

[rhettinger]

New changeset 9ddb777 by Raymond Hettinger (Miss Islington (bot)) in branch '3.8':
bpo-37158: Simplify and speed-up statistics.fmean() (GH-13832) (GH-13843)
9ddb777

[stevendaprano]

Nice! On my computer, I get about 30% speed up. Thanks Raymond.

The two PRs are status "merged". Does this mean we can close this ticket or is there more to do? (The git workflow is still a mystery to me.)

[rhettinger]

I can close it now :-)