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author | Raymond Hettinger <rhettinger@users.noreply.github.com> | 2022-08-29 04:41:58 (GMT) |
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committer | GitHub <noreply@github.com> | 2022-08-29 04:41:58 (GMT) |
commit | d8d55d13fc502ed79081e2c73d5d8cb034a8b577 (patch) | |
tree | aeb5dfe666c8363c0168306c849c897283eba90a | |
parent | 675e3470ccf3804a36a9cd451b813e9bd655aeb3 (diff) | |
download | cpython-d8d55d13fc502ed79081e2c73d5d8cb034a8b577.zip cpython-d8d55d13fc502ed79081e2c73d5d8cb034a8b577.tar.gz cpython-d8d55d13fc502ed79081e2c73d5d8cb034a8b577.tar.bz2 |
Prepare private _rank() function to be made public. (#96372)
-rw-r--r-- | Lib/statistics.py | 20 |
1 files changed, 15 insertions, 5 deletions
diff --git a/Lib/statistics.py b/Lib/statistics.py index a3f915c..b4676fe 100644 --- a/Lib/statistics.py +++ b/Lib/statistics.py @@ -355,7 +355,8 @@ def _fail_neg(values, errmsg='negative value'): raise StatisticsError(errmsg) yield x -def _rank(data, /, *, key=None, reverse=False, ties='average') -> list[float]: + +def _rank(data, /, *, key=None, reverse=False, ties='average', start=1) -> list[float]: """Rank order a dataset. The lowest value has rank 1. Ties are averaged so that equal values receive the same rank: @@ -369,14 +370,22 @@ def _rank(data, /, *, key=None, reverse=False, ties='average') -> list[float]: >>> _rank([3.5, 5.0, 3.5, 2.0, 6.0, 1.0]) [3.5, 5.0, 3.5, 2.0, 6.0, 1.0] - It is possible to rank the data in reverse order so that - the highest value has rank 1. Also, a key-function can - extract the field to be ranked: + It is possible to rank the data in reverse order so that the + highest value has rank 1. Also, a key-function can extract + the field to be ranked: >>> goals = [('eagles', 45), ('bears', 48), ('lions', 44)] >>> _rank(goals, key=itemgetter(1), reverse=True) [2.0, 1.0, 3.0] + Ranks are conventionally numbered starting from one; however, + setting *start* to zero allow the ranks to be used as array indices: + + >>> prize = ['Gold', 'Silver', 'Bronze', 'Certificate'] + >>> scores = [8.1, 7.3, 9.4, 8.3] + >>> [prize[int(i)] for i in _rank(scores, start=0, reverse=True)] + ['Bronze', 'Certificate', 'Gold', 'Silver'] + """ # If this function becomes public at some point, more thought # needs to be given to the signature. A list of ints is @@ -389,7 +398,7 @@ def _rank(data, /, *, key=None, reverse=False, ties='average') -> list[float]: if key is not None: data = map(key, data) val_pos = sorted(zip(data, count()), reverse=reverse) - i = 0 # To rank starting at 0 instead of 1, set i = -1. + i = start - 1 result = [0] * len(val_pos) for _, g in groupby(val_pos, key=itemgetter(0)): group = list(g) @@ -400,6 +409,7 @@ def _rank(data, /, *, key=None, reverse=False, ties='average') -> list[float]: i += size return result + def _integer_sqrt_of_frac_rto(n: int, m: int) -> int: """Square root of n/m, rounded to the nearest integer using round-to-odd.""" # Reference: https://www.lri.fr/~melquion/doc/05-imacs17_1-expose.pdf |