我支持使用显式的for循环和.extend()方法。
>>> import this
The Zen of Python, by Tim Peters
Beautiful is better than ugly.
Explicit is better than implicit.
...
Readability counts.
...
In the face of ambiguity, refuse the temptation to guess.
...
在测量时，普通的for循环比列表推导式中的副作用更快。
import itertools
import timeit
def flattenListOfLists(lst):
result = []
for sublist in lst:
result.extend(sublist)
return result
def flattenListOfLists2(lst):
result = []
[result.extend(sublist) for sublist in lst]
return result
def flattenIterTools(lst):
return list(itertools.chain(*lst))
a = ["a", "i", "u", "e", "o"]
k = ["ka", "ki", "ku", "ke", "ko"]
g = ["ga", "gi", "gu", "ge", "go"]
s = ["sa", "shi", "su", "se", "so"]
z = ["za", "ji", "zu", "ze", "zo"]
t = ["ta", "chi", "tsu", "te", "to"]
d = ["da", "du", "de", "do"]
n = ["na", "ni", "nu", "ne", "no"]
h = ["ha", "hi", "hu", "he", "ho"]
b = ["ba", "bi", "bu", "be", "bo"]
p = ["pa", "pi", "pu", "pe", "po"]
m = ["ma", "mi", "mu", "me", "mo"]
y = ["ya", "yu", "yo"]
n = ["n"]
kana = [a, k, g, s, z, t, d, n, h, b, p, m, y, n]
t = timeit.timeit('lst = flattenListOfLists(kana)', 'from __main__ import kana, flattenListOfLists', number=100000)
print 'for loop:', t
t = timeit.timeit('lst = flattenListOfLists2(kana)', 'from __main__ import kana, flattenListOfLists2', number=100000)
print 'list comprehension side effect:', t
t = timeit.timeit('lst = flattenIterTools(kana)', 'from __main__ import kana, flattenIterTools\nimport itertools', number=100000)
print 'itertools:', t
它会在我的控制台上打印输出:
for loop: 0.389831948464
list comprehension side effect: 0.468136159616
itertools: 0.620626692887
总之，时间就是重复100,000次同样的事情。易读性至关重要，这是我的论点。
