多对一映射（创建等价类）

发布于 2024-08-15 08:15:21 字数 927 浏览 5 评论 0原文

我有一个将一个数据库转换为另一个数据库的项目。原始数据库列之一定义了行的类别。该列应映射到新数据库中的新类别。

例如，假设原始类别是：parrot、spam、cheese_shop、Cleese、Gilliam、Palin

现在这对我来说有点冗长，我希望将这些行分类为 sketch， actor - 也就是说，将所有草图和所有演员定义为两个等价类。

>>> monty={'parrot':'sketch', 'spam':'sketch', 'cheese_shop':'sketch', 
'Cleese':'actor', 'Gilliam':'actor', 'Palin':'actor'}
>>> monty
{'Gilliam': 'actor', 'Cleese': 'actor', 'parrot': 'sketch', 'spam': 'sketch', 
'Palin': 'actor', 'cheese_shop': 'sketch'}

这很尴尬——我更喜欢这样的东西：

monty={ ('parrot','spam','cheese_shop'): 'sketch', 
        ('Cleese', 'Gilliam', 'Palin') : 'actors'}

但是，当然，这将整个元组设置为键：

>>> monty['parrot']

Traceback (most recent call last):
  File "<pyshell#29>", line 1, in <module>
    monty['parrot']
KeyError: 'parrot'

有什么想法如何在Python中创建优雅的多对一字典吗？

原文

I have a project of converting one database to another. One of the original database columns defines the row's category. This column should be mapped to a new category in the new database.

For example, let's assume the original categories are:parrot, spam, cheese_shop, Cleese, Gilliam, Palin

Now that's a little verbose for me, And I want to have these rows categorized as sketch, actor - That is, define all the sketches and all the actors as two equivalence classes.

>>> monty={'parrot':'sketch', 'spam':'sketch', 'cheese_shop':'sketch', 
'Cleese':'actor', 'Gilliam':'actor', 'Palin':'actor'}
>>> monty
{'Gilliam': 'actor', 'Cleese': 'actor', 'parrot': 'sketch', 'spam': 'sketch', 
'Palin': 'actor', 'cheese_shop': 'sketch'}

That's quite awkward- I would prefer having something like:

monty={ ('parrot','spam','cheese_shop'): 'sketch', 
        ('Cleese', 'Gilliam', 'Palin') : 'actors'}

But this, of course, sets the entire tuple as a key:

>>> monty['parrot']

Traceback (most recent call last):
  File "<pyshell#29>", line 1, in <module>
    monty['parrot']
KeyError: 'parrot'

Any ideas how to create an elegant many-to-one dictionary in Python?

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若无相欠,怎会相见 2024-08-22 08:15:21

在我看来，你有两个担忧。首先，你最初如何表达你的映射，即如何将映射键入到你的 new_mapping.py 文件中。其次，重映射过程中映射是如何工作的。这两种表示没有理由相同。

从您喜欢的映射开始：

monty = { 
    ('parrot','spam','cheese_shop'): 'sketch', 
    ('Cleese', 'Gilliam', 'Palin') : 'actors',
}

然后将其转换为您需要的映射：

working_monty = {}
for k, v in monty.items():
    for key in k:
        working_monty[key] = v

生成：

{'Gilliam': 'actors', 'Cleese': 'actors', 'parrot': 'sketch', 'spam': 'sketch', 'Palin': 'actors', 'cheese_shop': 'sketch'}

然后使用 working_monty 完成工作。

It seems to me that you have two concerns. First, how do you express your mapping originally, that is, how do you type the mapping into your new_mapping.py file. Second, how does the mapping work during the re-mapping process. There's no reason for these two representations to be the same.

Start with the mapping you like:

monty = { 
    ('parrot','spam','cheese_shop'): 'sketch', 
    ('Cleese', 'Gilliam', 'Palin') : 'actors',
}

then convert it into the mapping you need:

working_monty = {}
for k, v in monty.items():
    for key in k:
        working_monty[key] = v

producing:

{'Gilliam': 'actors', 'Cleese': 'actors', 'parrot': 'sketch', 'spam': 'sketch', 'Palin': 'actors', 'cheese_shop': 'sketch'}

then use working_monty to do the work.

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Saygoodbye 2024-08-22 08:15:21

您可以覆盖 dict 的索引器，但也许以下更简单的解决方案会更好：（

>>> assoc_list = ( (('parrot','spam','cheese_shop'), 'sketch'), (('Cleese', 'Gilliam', 'Palin'), 'actors') )
>>> equiv_dict = dict()
>>> for keys, value in assoc_list:
    for key in keys:
        equiv_dict[key] = value


>>> equiv_dict['parrot']
'sketch'
>>> equiv_dict['spam']
'sketch'

也许嵌套的 for 循环可以压缩为令人印象深刻的一行，但这有效并且可读。）

You could override dict's indexer, but perhaps the following simpler solution would be better:

>>> assoc_list = ( (('parrot','spam','cheese_shop'), 'sketch'), (('Cleese', 'Gilliam', 'Palin'), 'actors') )
>>> equiv_dict = dict()
>>> for keys, value in assoc_list:
    for key in keys:
        equiv_dict[key] = value


>>> equiv_dict['parrot']
'sketch'
>>> equiv_dict['spam']
'sketch'

(Perhaps the nested for loop can be compressed an impressive one-liner, but this works and is readable.)

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墨洒年华 2024-08-22 08:15:21

>>> monty={ ('parrot','spam','cheese_shop'): 'sketch', 
        ('Cleese', 'Gilliam', 'Palin') : 'actors'}

>>> item=lambda x:[z for y,z in monty.items() if x in y][0]
>>>
>>> item("parrot")
'sketch'
>>> item("Cleese")
'actors'

但我告诉你，它会比普通的一对一字典慢。

>>> monty={ ('parrot','spam','cheese_shop'): 'sketch', 
        ('Cleese', 'Gilliam', 'Palin') : 'actors'}

>>> item=lambda x:[z for y,z in monty.items() if x in y][0]
>>>
>>> item("parrot")
'sketch'
>>> item("Cleese")
'actors'

But let me tell you, It will be slow than normal one to one dictionary.

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