I'm just fiddling with this, am no great expert, but I added
def pairs5(x):
o=[]
for n in zip(x[::2],x[1:2]):
o.append(n)
return o
I dont know if that breaks any constraints placed on the problem, but I get
the following output
0.07158942896 0.266009705575 0.21342143313 0.0537146193457 0.0107680502972
does that make it faster than pairs(4) or am I breaking some constraints on
the problem?
Matt.
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Subject
Re:
pairs from a list
22/01/2008 18:09
Arnaud Delobelle wrote:
> pairs4 wins.
Oops. I see a smaller difference,
but yes, pairs4 wins.
Alan Isaac
import time
from itertools import islice, izip
x = range(500001)
def pairs1(x):
return izip(islice(x,0,None,2),islice(x,1,None,2))
def pairs2(x):
xiter = iter(x)
while True:
yield xiter.next(), xiter.next()
def pairs3(x):
for i in range( len(x)//2 ):
yield x[2*i], x[2*i+1],
def pairs4(x):
xiter = iter(x)
return izip(xiter,xiter)
t = time.clock()
for x1, x2 in pairs1(x):
pass
t1 = time.clock() - t
t = time.clock()
for x1, x2 in pairs2(x):
pass
t2 = time.clock() - t
t = time.clock()
for x1, x2 in pairs3(x):
pass
t3 = time.clock() - t
t = time.clock()
for x1, x2 in pairs4(x):
pass
t4 = time.clock() - t
print t1, t2, t3, t4
Output:
0.317524154606 1.13436847421 1.07100930426 0.262926712753
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