如何删除列表中的多余解析字符？

Question

我有以下列表列表：animals = [('dog', 'cat'), ('mouse', 'bird')]我想将其简化为：animals = ['dog', 'cat', 'mouse', 'bird']有没有比做这样的事情更简单的方法来获得上面的结果：animals = [('dog', 'cat'), ('mouse', 'bird')]final = []for a in animals:    final.append(a[0])    final.append(a[1])print final

Answer 1

您可以使用itertools.chain.from_iterable：

>>> from itertools import chain

>>> list(chain.from_iterable(animals))

['dog', 'cat', 'mouse', 'bird']

或嵌套的list comprehension：

>>> [anim for item in animals for anim in item]

['dog', 'cat', 'mouse', 'bird']

对于小型列表，请使用列表理解版本，否则请使用itertools.chain.from_iterable。

>>> animals = [('dog', 'cat'), ('mouse', 'bird')]

>>> %timeit list(chain.from_iterable(animals))

100000 loops, best of 3: 2.31 us per loop

>>> %timeit [anim for item in animals for anim in item]

1000000 loops, best of 3: 1.13 us per loop

>>> animals = [('dog', 'cat'), ('mouse', 'bird')]*100

>>> %timeit list(chain.from_iterable(animals))

10000 loops, best of 3: 31.5 us per loop

>>> %timeit [anim for item in animals for anim in item]

10000 loops, best of 3: 73.7 us per loop

>>> animals = [('dog', 'cat'), ('mouse', 'bird')]*1000

>>> %timeit list(chain.from_iterable(animals))

1000 loops, best of 3: 296 us per loop

>>> %timeit [anim for item in animals for anim in item]

1000 loops, best of 3: 733 us per loop