Python，使用通配符访问字典 [英] Python, accessing dictionary with wildcards

问题描述

我有一本包含项的字典，其中的键是某种正则表达式.我正在寻找一个只要传递匹配字符串就返回匹配项列表的函数

I have a dictionary with items, where the keys are some kind of regular expressions. I am looking for a function to return a list of matching items whenever a matching string is passed

d = {'a.b': item1, 'b.c':item2}

func(d,'a1b')
>>> [item1]

func(d,'b2c')
>>> [item2]

有没有一种pythonic的方法来做到这一点?我唯一能想到的解决方案是:

Is there a pythonic way to do this ? The only solution I can come up with is:

import re
def func(d, event):
    res = list()
    for key, item in d.iteritems():
        if re.match(key, event):
            res.append(item)
    return res

推荐答案

您可以创建一个包装字典类的类，该类将为您完成:

You can create a class that will do that for you that wraps the dictionary class:

import re

class RegexDict(dict):

    def get_matching(self, event):
        return (self[key] for key in self if re.match(key, event))

使用示例:

>>> d = {'a.b': 'item1', 'b.c': 'item2'}
>>> rd = RegexDict(d)
>>> for o in rd.get_matching('a1b'):
    print o


item1

这省去了依赖外部功能的麻烦，使开销较小，并且更健壮.

This saves you having to rely on external functions, it keeps the overhead small, and is more robust.

您还可以添加另一个函数，该函数将列表(或iter)作为输入并返回所有匹配的值:

You could also add another function that takes a list (or iter) as input and returns all matching values:

    def get_all_matching(self, events):
        return (match for event in events for match in self.get_matching(event))

>>> for o in rd.get_all_matching(['a1b', 'b2c']):
    print o


item1
item2

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