Compare implementations of islice

gistfile1.py

from timeit import timeit

setup = '''
l = range(20)
def islice(iterable, *args):
    # islice('ABCDEFG', 2) --> A B
    # islice('ABCDEFG', 2, 4) --> C D
    # islice('ABCDEFG', 2, None) --> C D E F G
    # islice('ABCDEFG', 0, None, 2) --> A C E G
    s = slice(*args)
    it = iter(xrange(s.start or 0, s.stop or sys.maxint, s.step or 1))
    nexti = next(it)
    for i, element in enumerate(iterable):
        if i == nexti:
            yield element
            nexti = next(it)

qslice = (x for x, idx in zip(l, range(0, len(l))) if 10 <= idx < 15)
rslice = (x for idx, x in enumerate(l) if 10 <= idx < 15)
'''

exec(setup)
list_islice = list(islice(l, 10, 15))
list_qslice = list(qslice)
list_rslice = list(rslice)
assert list_islice == list_qslice, (list_islice, list_qslice)
assert list_islice == list_rslice, (list_islice, list_rslice)
assert list_rslice == list_qslice, (list_rslice, list_qslice)

print '1M iterations of islice(l, 10, 15): %f' % timeit('islice(l, 10, 15)', setup, number=10**6)
print '1M iterations of (x for x, idx in zip(l, range(0, len(l))) if 10 <= idx < 15): %f' % timeit('(x for x, idx in zip(l, range(0, len(l))) if 10 <= idx < 15)', setup, number=10**6)
print '1M iterations of (x for idx, x in enumerate(l) if 10 <= idx < 15): %f' % timeit('(x for idx, x in enumerate(l) if 10 <= idx < 15)', setup, number=10**6)

print '1M iterations of list(islice(l, 10, 15)): %f' % timeit('list(islice(l, 10, 15))', setup, number=10**6)
print '1M iterations of list((x for x, idx in zip(l, range(0, len(l))) if 10 <= idx < 15)): %f' % timeit('list((x for x, idx in zip(l, range(0, len(l))) if 10 <= idx < 15))', setup, number=10**6)
print '1M iterations of list((x for idx, x in enumerate(l) if 10 <= idx < 15)): %f' % timeit('list((x for idx, x in enumerate(l) if 10 <= idx < 15))', setup, number=10**6)

# 1M iterations of islice(l, 10, 15): 0.629101
# 1M iterations of (x for x, idx in zip(l, range(0, len(l))) if 10 <= idx < 15): 3.772903
# 1M iterations of (x for idx, x in enumerate(l) if 10 <= idx < 15): 1.280824
# 1M iterations of list(islice(l, 10, 15)): 7.466557
# 1M iterations of list((x for x, idx in zip(l, range(0, len(l))) if 10 <= idx < 15)): 8.542739
# 1M iterations of list((x for idx, x in enumerate(l) if 10 <= idx < 15)): 6.021005