如何访问字典中的第一个和最后一个元素?

本文介绍了如何访问字典中的第一个和最后一个元素?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

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)