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authorRaymond Hettinger <rhettinger@users.noreply.github.com>2018-11-09 10:39:50 (GMT)
committerMiss Islington (bot) <31488909+miss-islington@users.noreply.github.com>2018-11-09 10:39:50 (GMT)
commit0a18e0510a145427d8ff1864a011c81ea02cdcd4 (patch)
tree1f9e4f52be6672e8fc802e0276c4638db1eaf28c
parentcf5863faabe011a61827b9b9982dba3d6a381f0f (diff)
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Hoist the float conversion out of the inner loop. (GH-10430)
Currently, the *n* and *total* variables get converted to floats each time they are multiplied by random(). This minor tweak does the conversion just once and gets a small speedup (approx 3%).
-rw-r--r--Lib/random.py3
1 files changed, 2 insertions, 1 deletions
diff --git a/Lib/random.py b/Lib/random.py
index b2c0d6f..4b51b66 100644
--- a/Lib/random.py
+++ b/Lib/random.py
@@ -375,6 +375,7 @@ class Random(_random.Random):
if cum_weights is None:
if weights is None:
_int = int
+ n += 0.0 # convert to float for a small speed improvement
return [population[_int(random() * n)] for i in range(k)]
cum_weights = list(_itertools.accumulate(weights))
elif weights is not None:
@@ -382,7 +383,7 @@ class Random(_random.Random):
if len(cum_weights) != n:
raise ValueError('The number of weights does not match the population')
bisect = _bisect.bisect
- total = cum_weights[-1]
+ total = cum_weights[-1] + 0.0 # convert to float
hi = n - 1
return [population[bisect(cum_weights, random() * total, 0, hi)]
for i in range(k)]