如何避免覆盖字典追加? [英] How to avoid overwrite for dictionary append?

问题描述

例如，我有:

dic={'a': 1, 'b': 2, 'c': 3}

现在，我想再添加一个'c':4到字典中.它将覆盖现有的'c':3.

Now I'd like another 'c':4 add into dictionary. It'll overwrite the existing 'c':3.

我怎么能得到dic?

dic={'a': 1, 'b': 2, 'c': 3, 'c':4}

推荐答案

字典键必须是唯一的.但是您可以将列表作为值，这样就可以在其中存储多个值.可以通过使用collections.defaultdict来实现，如下所示. (示例是从IPython会话复制的.)

Dictionary keys must be unique. But you can have a list as a value so you can store multiple values in it. This can be accomplished by using collections.defaultdict as shown below. (Example copied from IPython session.)

In [1]: from collections import defaultdict

In [2]: d = defaultdict(list)

In [3]: d['a'].append(1)

In [4]: d['b'].append(2)

In [5]: d['c'].append(3)

In [6]: d['c'].append(4)

In [7]: d
Out[7]: defaultdict(list, {'a': [1], 'b': [2], 'c': [3, 4]})

这篇关于如何避免覆盖字典追加?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！