bpo-21592: Implement non recursive quickselect for statistics.py #6715
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corona10
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scoder
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May 7, 2018
Lib/statistics.py
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| @@ -373,15 +393,20 @@ def median(data): | |||
| 4.0 | |||
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| """ | |||
| data = sorted(data) | |||
| data = [d for d in data] | |||
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Why is this not calling list(data)?
scoder
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May 7, 2018
Lib/statistics.py
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| else: | ||
| i = n//2 | ||
| return (data[i - 1] + data[i])/2 | ||
| return _quick_select(data, 0, n-1, pos-1)/2 + _quick_select(data, 0, n-1, pos)/2 |
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I'd be surprised if there wasn't a way to avoid doing the whole expensive operation twice.
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@scoder Thank you for review, I updated it. |
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I read some of not merged PR for this issue.
All of them are recursive versions which can cause a stack overflow.
This version is an iterative version which can avoid this issue.
https://bugs.python.org/issue21592