如果mydict不为空,则访问任意元素,如下:
mydict[mydict.keys()[0]]
还有什么更好的办法吗?
如果mydict不为空,则访问任意元素,如下:
mydict[mydict.keys()[0]]
还有什么更好的办法吗?
当前回答
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()))
其他回答
first_key, *rest_keys = mydict
在python3
list(dict.values())[0]
在Python 3中,非破坏性和迭代性:
next(iter(mydict.values()))
在Python 2中,非破坏性和迭代性:
mydict.itervalues().next()
如果你想让它在python2和python3中都能工作,你可以使用six包:
six.next(six.itervalues(mydict))
虽然在这一点上,它是相当神秘的,我更喜欢你的代码。
如果你想删除任何项目,请执行以下操作:
key, value = mydict.popitem()
请注意,“first”在这里可能不是一个合适的术语,因为dict在Python < 3.6中不是有序类型。Python 3.6+字典是有序的。
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。
为了得到钥匙
next(iter(mydict))
得到一个值
next(iter(mydict.values()))
两者兼得
next(iter(mydict.items())) # or next(iter(mydict.viewitems())) in python 2
前两个是Python 2和3。后两个在python3中是lazy,但在python2中不是。