def init_set8(r10=range(10)):
"""
把循环内的range函数提到外面
times5.486 ==> 4.427
"""
ret = []
for i in r10:
for j in r10:
for k in r10:
for l in r10:
if i != j and i != k and i != l and j != k and j != l and k != l:
ret.append((i, j, k, l))
return ret
timing(init_set8, 1000)
def init_set9(r10=range(10)):
"""
for 循环改成列表推导
times5.486 ==>3.773
"""
return [(i, j, k, l)
for i in r10
for j in r10
for k in r10
for l in r10
if ( i != j and i != k and i != l and j != k and j != l and k != l) ]
timing(init_set9, 1000)
def init_set10(r10=range(10)):
return ((i, j, k, l)
for i in r10
for j in r10
for k in r10
for l in r10
if( i != j and i != k and i != l and j != k and j != l and k != l) )
timing(init_set10, 1000)
def init_set11():
"""
用代码的空间代价换取计算P4_4的时间
init_set11 1000 times 7.268 OMG
reduce(lambda x,y:x+y,l)太慢了
"""
c10_4=[( i, j, k, l ) for i in xrange(0, 10)
for j in xrange(i+1, 10)
for k in xrange(j+1, 10)
for l in xrange(k+1, 10) ]
ret=reduce(lambda x,y:x+y,
[ [ (i, j, k, l),
(i, j, l, k),
(i, k, j, l),
(i, k, l, j),
(i, l, j, k),
(i, l, k, j),
(j, i, k, l),
(j, i, l, k),
(j, k, i, l),
(j, k, l, i),
(j, l, i, k),
(j, l, k, i),
(k, i, j, l),
(k, i, l, j),
(k, j, i, l),
(k, j, l, i),
(k, l, i, j),
(k, l, j, i),
(l, i, j, k),
(l, i, k, j),
(l, j, i, k),
(l, j, k, i),
(l, k, i, j),
(l, k, j, i),]
for i, j, k, l in c10_4 ],
)
return ret
def init_set12():
"""
generator是伟大的发明,数据流编程万岁
init_set12 1000 times 1.758
www.iplaypy.com
"""
c10_4=(( i, j, k, l ) for i in xrange(0, 10)
for j in xrange(i+1, 10)
for k in xrange(j+1, 10)
for l in xrange(k+1, 10) )
from itertools import chain
ret=chain(
*( ( (i, j, k, l),
(i, j, l, k),
(i, k, j, l),
(i, k, l, j),
(i, l, j, k),
(i, l, k, j),
(j, i, k, l),
(j, i, l, k),
(j, k, i, l),
(j, k, l, i),
(j, l, i, k),
(j, l, k, i),
(k, i, j, l),
(k, i, l, j),
(k, j, i, l),
(k, j, l, i),
(k, l, i, j),
(k, l, j, i),
(l, i, j, k),
(l, i, k, j),
(l, j, i, k),
(l, j, k, i),
(l, k, i, j),
(l, k, j, i),)
for i, j, k, l in c10_4 )
)
return list(ret)
timing(init_set12, 1000)