字典列表，在字典中 - 在 Python 中
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List of dictionaries, in a dictionary - in Python
提问by Terry Felkrow
I have a case where I need to construct following structure programmatically(yes I am aware of .setdefault and defaultdict but I can not get what I want)
我有一个案例，我需要以编程方式构建以下结构（是的，我知道 .setdefault 和 defaultdict 但我无法得到我想要的）
I basically need a dictionary, with a dictionary of dictionaries created within the loop. At the beginning the structure is completely blank.
我基本上需要一个字典，在循环中创建一个字典。一开始，结构是完全空白的。
structure sample (please note, I want to create an array that has this structure in the code!)
结构示例（请注意，我想在代码中创建一个具有此结构的数组！）
RULE = {
'hard_failure': {
4514 : {
'f_expr' = 'ABC',
'c_expr' = 'XF0',
}
}
}
pseudo code that needs to create this:
需要创建这个的伪代码：
...
self.rules = {}
for row in rows:
a = 'hard_failure'
b = row[0] # 4514
c = row[1] # ABC
d = row[2] # XF0
# Universe collapse right after
self.rules = ????
...
The code above is obviously not working since I dont know how to do it!
上面的代码显然不起作用，因为我不知道该怎么做！
回答by SilentGhost
Example, that you've posted is not a valid python code, I could only imagine that you're trying to do something like this:
例如，您发布的不是有效的 Python 代码，我只能想象您正在尝试执行以下操作：
self.rules[a] = [{b:{'f_expr': c, 'c_expr': d}}]
this way self.rulesis a dictionary of a list of a dictionary of a dictionary. I bet there is more sane way to do this.
这种方式self.rules是字典的字典列表的字典。我敢打赌有更明智的方法来做到这一点。
回答by Arthur Thomas
rules = {}
failure = 'hard_failure'
rules[failure] = []
for row in rows:
#this is what people are referring to below. You left out the addition of the dictionary structure to the list.
rules[failure][row[0]] = {}
rules[failure][row[0]]['type 1'] = row[1]
rules[failure][row[0]]['type 2'] = row[2]
This is what I created based on how I understood the questions. I wasn't sure what to call the 'f_expr' and 'c_expr' since you never mention where you get those but I assume they are already know column names in a resultset or structure of some sort.
这是我根据我对问题的理解创建的。我不确定如何称呼 'f_expr' 和 'c_expr' 因为你从来没有提到你从哪里得到它们，但我认为它们已经知道结果集或某种结构中的列名。
Just keep adding to the structure as you go.
继续添加到结构中。
回答by Terry Felkrow
Well, I apologize for the confusion, I never claimed that code actually compiled, hence (pseudo). Arthur Thomas put me on the right track, here is slightly modified version. (Yes, now its a simply nested dictionary, 3 levels down)
好吧，我为造成的混乱道歉，我从未声称代码实际上已编译，因此（伪）。亚瑟·托马斯让我走上了正轨，这里是稍作修改的版本。（是的，现在它是一个简单的嵌套字典，向下 3 级）
RULE_k = 'hard_failure'
self.rules = {}
for row in rows:
self.rules_compiled.setdefault(RULE_k, {})
self.rules_compiled[RULE_k][row[1]] = {}
self.rules_compiled[RULE_k][row[1]]['f_expr'] = row[0]
self.rules_compiled[RULE_k][row[1]]['c_expr'] = row[1]
回答by Dave Webb
Your example code doesn't seem to be valid Python. It's not clear if the second level element is supposed to be a list or a dictionary.
您的示例代码似乎不是有效的 Python。不清楚第二级元素应该是列表还是字典。
However, if you're doing what I think you're doing, and it's a dictionary, you could use a tuple as a key in the top-level dictionary instead of nesting dictionaries:
但是，如果你正在做我认为你正在做的事情，并且它是一个字典，你可以使用元组作为顶级字典中的键，而不是嵌套字典：
>>> a = 'hard_failure'
>>> b = 4514
>>> c = "ABC"
>>> d = "XF0"
>>> rules = {}
>>> rules[(a,b)] = {'f_expr' : a,'c_expr' : d}
>>> rules
{('hard_failure', 4514): {'c_expr': 'XF0', 'f_expr': 'hard_failure'}}
回答by Pete
My favorite way to deal with nested dictionaries & lists of dictionaries is to use PyYAML. See this response for details.
我最喜欢处理嵌套字典和字典列表的方法是使用PyYAML。 有关详细信息，请参阅此回复。
