返回由生成器或迭代器生成的所有元素的标准方法

Question

I'm looking for a neat, ideally standard-library-based method or recipe for turning an iterator or generator object into a list containing all the elements that you would get if you iterated over this object. If there are any different solutions regarding Python 2.7 or 3.x I'd also be interested in knowing. Basically, I'm looking for something functionally equivalent to:

def expand(obj):
    result = []
    for o in obj:
        result.append(o)
    return result

I understand that generators and iterators in Python come with lots of benefits, and that this probably shouldn't be used in .py files. However, I do think this has its uses, especially when programming interactively and when using small datasets for testing.

My best answer so far is list comprehension:

In [55]: a=[1,2,3]
In [56]: r=reversed(a)
In [57]: r
Out[57]: <listreverseiterator at 0x101f51a10>

In [58]: [x for x in r]
Out[58]: [3, 2, 1]

In [59]: def f(x):
   ....:     while x > 0:
   ....:         x-=1
   ....:         yield x
   ....:         

In [60]: [x for x in f(4)]
Out[60]: [3, 2, 1, 0]

I've tried searching Google and StackOverflow without finding anything obvious, and I've checked the itertools and functools docs - most of my attempts based on those just result in more objects. I also had a quick look at IPython magicks , but didn't notice anything obvious there.

Answer 1

有一个非常简单的解决方案： list(the_iterator)