[Feature Request] XPath support

[jimustafa]

Is your feature request related to a problem? Please describe.
For files with a complex object hierarchy, it can sometimes be difficult to select a subset of objects based on their path or attributes.

Describe the solution you'd like
Given that an H5 file has an object hierarchy, it may be possible to implement functionality to access objects using XPath expressions. This has also been discussed briefly in h5py/h5py#932. Probably a big ask, but likely still worth consideration.

Describe alternatives you've considered
None yet. Open to suggestions.

Additional context
None.

[qkoziol]

Any pointer to XPath, so I could think about this more?

[jimustafa]

Some resources that I have used in the past include:

• https://www.w3schools.com/xml/xpath_intro.asp
• https://www.tutorialspoint.com/xpath/
• https://docs.python.org/3/library/xml.etree.elementtree.html#xpath-support

One way to play around with XPath would be to copy some XML from somewhere like https://www.w3schools.com/xml/xpath_examples.asp (books.xml) into an XPath tester, such as http://xpather.com/.