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https://codeberg.org/rimu/pyfedi
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50 lines
1.1 KiB
Python
50 lines
1.1 KiB
Python
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# from https://medium.com/hacking-and-gonzo/how-reddit-ranking-algorithms-work-ef111e33d0d9
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from math import sqrt, log
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from datetime import datetime, timedelta
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epoch = datetime(1970, 1, 1)
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def epoch_seconds(date):
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td = date - epoch
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return td.days * 86400 + td.seconds + (float(td.microseconds) / 1000000)
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def score(ups, downs):
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return ups - downs
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# used for ranking stories
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def hot(ups, downs, date):
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s = score(ups, downs)
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order = log(max(abs(s), 1), 10)
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sign = 1 if s > 0 else -1 if s < 0 else 0
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seconds = epoch_seconds(date) - 1134028003 # this value seems to be an arbitrary time in 2005.
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return round(sign * order + seconds / 45000, 7)
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# used for ranking comments
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def _confidence(ups, downs):
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n = ups + downs
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if n == 0:
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return 0
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z = 1.281551565545
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p = float(ups) / n
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left = p + 1 / (2 * n) * z * z
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right = z * sqrt(p * (1 - p) / n + z * z / (4 * n * n))
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under = 1 + 1 / n * z * z
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return (left - right) / under
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def confidence(ups, downs):
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if ups + downs == 0:
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return 0
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else:
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return _confidence(ups, downs)
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