python的递归itemgetter

问题描述

python 中是否有递归的 itemgetter.假设你有一个像

Is there a recursive itemgetter in python. Let's say you have an object like

d = {'a': (1,2,3), 'b': {1: (5,6)}}

我想从 d['a'] 获取元组的第一个元素?据我所知 itemgetter 只会做一个级别，即获取我 a 或 b 或两者.

and I wanted to get the first element of the tuple from d['a']? As far as I can tell itemgetter will only do one level, i.e. get me a or b or both.

是否有一些巧妙的方法将 itertools 与 itemgetter 结合以产生所需的结果.

Is there some clever way of combining itertools with itemgetter to produce the desired result.

所以基本上我想要能够调用的是

So basically what I want to be able to call is

from operator import itemgetter
d = {'a': (1,2), 'b': (4, (5,))}
itemgetter({'a': 0})(d) --> 1
itemgetter({'b': 0})(d) --> 4
itemgetter({'b': {1: 0}})(d) --> 5

d = {'a': {'b': (1,2,3)}}
itemgetter({'a': {'b': 2}})(d) --> 3

推荐答案

我不喜欢聪明"的方式.明显更好.

I don't like 'clever' ways. Obvious is better.

您可以非常轻松地编写一个沿下标列表迭代的 getter:

You can very easily write a getter that iterates along a list of subscripts:

def getter(x, *args):
    for k in args:
        x = x[k]
    return x

>>> d = {'a': (1,2,3), 'b': {1: (5,6)}}
>>> getter(d, 'a', 0)
1

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