我刚写了这段代码,我想知道为什么它在Python 3中表现得更差?所有平台都一样吗?这只是运气不好,还是Py3通常较慢?
谢谢!
性能:
python 2.6 python 3.1 pypy 1.5
linux 2.2s 2.4s 0.8s
os x 2.5s 3.4s 0.7s
代码:(对不起,这太仓促和低效!)
import itertools
import random
def fptp_draw(result):
votes = [prefs[0] for prefs in result]
counts = [len([v for v in votes if v == c]) for c in [1, 2, 3]]
s = sorted(counts)
#print('fptp', counts)
return s[-1] == s[-2]
def av_remove(prefs, cand):
if prefs[0] != cand:
return prefs
else:
return prefs[1:]
def av_draw(result):
nv = len(result)
cands = [1, 2, 3]
while True:
votes = [prefs[0] for prefs in result]
counts = [len([v for v in votes if v == c]) for c in cands]
#print('av ', cands, counts)
s = sorted(counts)
if s[-1]*2 > nv:
return False
if len(cands) == 2:
return True
loser = cands[counts.index(s[0])]
cands.remove(loser)
result = [av_remove(prefs, loser) for prefs in result]
return False
#orders = list(itertools.permutations([1, 2, 3]))
orders = [[1, 2, 3], [1, 3, 2], [2, 1, 3], [2, 3, 1], [3, 1, 2], [3, 2, 1]]
#results = list(itertools.product(*itertools.repeat(orders, 6)))
#results = random.sample(results, 5)
def rand_vote():
return [random.choice(orders) for i in range(1000)]
n = fptp = av = 0
for j in range(1000):
r = rand_vote()
#print()
#print(r)
n += 1
if fptp_draw(r):
fptp += 1
if av_draw(r):
av += 1
print(fptp*100.0/n, av*100.0/n)
print(n)
答案 0 :(得分:4)
Py3k通常是slower而不是python 2.x.随着时间的推移,这将会改变,但py3k的重点是功能完整性和稳定性,而不是速度。
答案 1 :(得分:1)
我想我已经回答了我自己的问题:
3.0概括的最终结果是Python 3.0运行pystone基准测试比Python 2.5慢大约10%。最有可能的最大原因是为小整数移除了特殊套管。还有改进的余地,但会在3.0发布后发生!
编辑:虽然令人惊讶的是它在OS X上的性能提升了40%......