发布之前,我已经经历过>访问字典中的任意元素在Python中,但对此我不确定.
Before posting, I have already gone through Access an arbitrary element in a dictionary in Python, butI'm uncertain about this.
我有一个很长的字典,我必须获取它的第一个和最后一个键的值.我可以使用dict[dict.keys()[0]]和dict[dict.keys()[-1]]来获取第一个和最后一个元素,但是由于key:value对是以随机形式输出的(如key:value对的位置是随机的),将提供解决方案吗在此链接中始终有效吗?
I have a long dictionary and I've to get the values of its first and last keys. I can use dict[dict.keys()[0]] and dict[dict.keys()[-1]] to get the first and last elements, but since the key:value pairs are outputted in a random form(as in the positioning of the key:value pairs is random), will the solution provided in this link always work?
推荐答案使用 OrderedDict ,因为普通字典在遍历时不会保留其元素的插入顺序.方法如下:
Use an OrderedDict, because a normal dictionary doesn't preserve the insertion order of its elements when traversing it. Here's how:
# import the right class from collections import OrderedDict # create and fill the dictionary d = OrderedDict() d['first'] = 1 d['second'] = 2 d['third'] = 3 # retrieve key/value pairs els = list(d.items()) # explicitly convert to a list, in case it's Python 3.x # get first inserted element els[0] => ('first', 1) # get last inserted element els[-1] => ('third', 3)更多推荐
如何访问字典中的第一个和最后一个元素?
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