[英]Sort subset of dictionary keys
How do i sort the following list B that is a subset of dictionary A, based on A's values? 如何根据A的值对作为词典A子集的以下列表B进行排序?
A = {1: 10, 2:20, 3: 15, 4: 1}
B = [1, 3, 4]
My solution should be 我的解决方案应该是
B = [4, 1, 3]
since 以来
A[4] < A[1] < A[3]
Use A.get
as key
使用
A.get
作为key
A = {1: 10, 2:20, 3: 15, 4: 1}
B = [1, 3, 4]
>>> sorted(B, key=A.get)
[4, 1, 3]
Notice that you can set a default value as argument for the .get
method, such that, if a given key doesn't exist in your dict, you can set a position yourself (eg last position or first). 请注意,您可以将默认值设置为
.get
方法的参数,这样,如果字典中不存在给定键,则您可以自己设置位置(例如,最后一个位置或第一个位置)。 For example: 例如:
B = [1, 3, 4, 11]
>>> sorted(B, key=lambda k: A.get(k, -1))
[11, 4, 1, 3]
>>> sorted(B, key=lambda k: A.get(k, float('inf')))
[4, 1, 3, 11]
Or, as highlighted by @jpp, 或者,如@jpp突出显示的那样,
>>> sorted(B, key=A.__getitem__)
if you prefer a KeyError
to be raised if referenced key doesn't exist. 如果您更喜欢在引用的键不存在的情况下引发
KeyError
。
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