另一种方法是在一行中做到这一点，同时保持字典的完整性:

arbitrary_value = mydict.setdefault(*mydict.popitem())

popitem() returns a tuple of (key, value) for the last item that was added into the dictionary and this pair is passed into setdefault as positional arguments. The setdefault tries to insert key into mydict with value value if it doesn't already exist, but does nothing if does exist; and then returns the value of that key to the caller. Because we already popped the (key, value) pair out of the dictionary, we insert it back into it via setdefault and then proceed to return value, which is what we want.

另一种方法是在一行中做到这一点，同时保持字典的完整性:

arbitrary_value = mydict.setdefault(*mydict.popitem())

popitem() returns a tuple of (key, value) for the last item that was added into the dictionary and this pair is passed into setdefault as positional arguments. The setdefault tries to insert key into mydict with value value if it doesn't already exist, but does nothing if does exist; and then returns the value of that key to the caller. Because we already popped the (key, value) pair out of the dictionary, we insert it back into it via setdefault and then proceed to return value, which is what we want.

忽略字典排序的问题，这样可能会更好:

next(dict.itervalues())

这样就避免了项查找和生成不使用的键的列表。

Python3

next(iter(dict.values()))

first_key, *rest_keys = mydict

As others mentioned, there is no "first item", since dictionaries have no guaranteed order (they're implemented as hash tables). If you want, for example, the value corresponding to the smallest key, thedict[min(thedict)] will do that. If you care about the order in which the keys were inserted, i.e., by "first" you mean "inserted earliest", then in Python 3.1 you can use collections.OrderedDict, which is also in the forthcoming Python 2.7; for older versions of Python, download, install, and use the ordered dict backport (2.4 and later) which you can find here.

Python 3.7 现在字典是按插入顺序排列的。

在python3

list(dict.values())[0]