如何检查python字典内的内部字典中是否存在键? [英] How to check if a key exists in an inner dictionary inside a dictionary in python?

问题描述

有一个python字典:

There is a python dictionary:

a = {b:{c:{"x":1, "y":2, "z":3}}}

我想知道 a [b] [c] ["z"] 是否存在，但我不知道 a [b] [c] 或 a [b] 是否存在.

I want to know if a[b][c]["z"] exists, but yet I don't know if a[b][c] or a[b] exist either.

所以，如果我这样做:

if "z" in a[b][c]:

我可能会收到"a [b]" 中不存在键c或"a" 错误中不存在键b.

I may get a "key c doesn't exist in a[b]" or "key b doesn't exist in a" error.

在这种情况下，如何正确检查a [b] [c]中是否存在z?

How to properly check if z exists in a[b][c] in this case?

推荐答案

如果由于某种原因(例如lambda func，列表理解，生成器表达式等)而无法使用异常

IF you can't use an exception for some reason (eg. lambda func, list comprehension, generator expression etc)

value = a.get(b, {}).get(c, {}).get("z", None)

但是通常您应该更喜欢使用异常处理程序

But normally you should prefer to use the exception handler

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