n00m schrieb:
Any comment:
class Vector:
def __init__(self, x, y):
self.x = x
self.y = y
def __cmp__(self, v):
if self.x < v.x and self.y > v.y:
return -1
return 0
def v_cmp(v1, v2):
if v1.x < v2.x and v1.y > v2.y:
return -1
return 0
from random import randint
from time import time
a = []
for i in range(200000):
Use xrange instead (unless you are under python3), because for loops you
don't need the full list range creates - xrange is just a generator.
a += [Vector(randint(0, 500000), randint(0, 500000))]
Better use .append here, looks nicer and should also be a bit faster.
b = a[:]
c = a[:]
print 'Sorting...'
t = time()
b.sort(cmp=v_cmp)
print time() - t
t = time()
c.sort()
print time() - t
print b == c
===================================== RESTART ======
Sorting...
0.906000137329
6.57799983025
I think the main reason is that method-dispatch is more expensive than
function-dispatch. The former must create a bound method before calling,
the latter just works out of the box.
Things get better if you do this:
t = time()
c.sort(cmp=Vector.__cmp__)
print time() - t
Although not the exact same performance - I get
Sorting...
0.677843093872
1.4283311367
True
Diez
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