python 可迭代对象与迭代器之间的转换

列表：

 >>> l = [1, 2, 3, 4]
 >>> l_iter = iter(l)
 >>> l_iter
 <list_iterator object at 0x10199e860>
 >>> l = list(l_iter)
 >>> l
 [1, 2, 3, 4]

字符串：

 >>> s = 'abcdef'
 >>> l = list(s)
 >>> l
 ['a', 'b', 'c', 'd', 'e', 'f']
 >>> i = iter(l)
 >>> i
 <list_iterator object at 0x10199e8d0>
 >>> s = ''.join(l)
 >>> s
 'abcdef'
 >>> s = ''.join(i)
 >>> s
 'abcdef'

字典：

 >>> d = dict(one=1, two=2)
 >>> d
 {'one': 1, 'two': 2}
 >>> i = iter(d)
 >>> i
 <dict_keyiterator object at 0x1019a6458>    # 键值得迭代器
 >>> for k in i:
 ...     print(k)
 ...
 one
 two

元组：

 >>> t = (1, 2, 3, 4)
 >>> t_iter = iter(t)
 >>> t_iter
 <tuple_iterator object at 0x10199eb00>
 >>> t = tuple(t_iter)
 >>> t
 (1, 2, 3, 4)

集合：

 >>> s = {1, 2, 3, 4}
 >>> s_iter = iter(s)
 >>> s_iter
 <set_iterator object at 0x1019a5d38>
 >>> s = set(s_iter)
 >>> s
 {1, 2, 3, 4}