英文:
Managing square brackets in dictionary keys with dpath library
问题
使用dpath库时，我在处理包含方括号键的字典时遇到了问题。从文档中我看到方括号被视为正则表达式的元素。然而，在我的情况下，这导致了问题，因为我只想它们是"普通"的方括号。
我尝试用反斜杠\[转义方括号，但结果仍然相同。
代码示例
import dpath
d = {'Position': {'Position x [mm]': 3}}
dpath.search(d, 'Position/Position x [mm]/*')
这会输出：{}而不是预期的{'Position': {'Position x [mm]': 3}}。
英文:
Using the dpath library, I'm having trouble working with a dictionary with keys containing square brackets. From the docs I see that square brackets are considered as elements of regular exporessions. However, this is causing the issue in my case, because I just want them to be "normal" square brackets.
I tried to escape the square brackets with a backspace \[, but the result is the same.
Code example
import dpath
d = {'Position': {'Position x [mm]': 3}}
dpath.search(d, 'Position/Position x [mm]/*')
This outputs: {} instead of the expected {'Position': {'Position x [mm]': 3}}
Maybe there is already a solution for the problem, but I did not find it in the docs.
答案1
得分: 3
看起来dpath在底层使用了*fnmatch*库（fnmatch模块提供对Unix shell风格的通配符的支持，这与正则表达式不同）。根据fnmatch文档的描述，
对于字面匹配，请将元字符括在方括号中。例如，'
[?]'匹配字符'?'。
因此，您需要将[替换为[[]，将]替换为[]]以获得期望的匹配结果。
>>> import dpath
>>>
>>> d = {'Position': {'Position x [mm]': 3}}
>>> dpath.search(d, 'Position/Position x [[]mm[]]')
{'Position': {'Position x [mm]': 3}}
英文:
It seems like dpath uses fnmatch library under the hood(fnmatch module provides support for Unix shell-style wildcards, which are not the same as regular expressions). As per the fnmatch documentation,
> For a literal match, wrap the meta-characters in brackets. For
> example, '[?]' matches the character '?'
So you have to replace the [ with [[] and ] with []] to get the expected match result.
>>> import dpath
>>>
>>> d = {'Position': {'Position x [mm]': 3}}
>>> dpath.search(d, 'Position/Position x [[]mm[]]')
{'Position': {'Position x [mm]': 3}}
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