Dim slicer

[pp-mo]

Closes #68
Closes #161
Closes #166

[pp-mo]

Update:

Fixed variable comparison for newly-added "no-data" variable testcases
and added testing for the new usage.

Still WIP/TODO:

we now have the beginnings of a strategy to run a set of testcases through both the ncdata.utils.index_by_dimensions and the ncdata.utils.Slicer APIs.
So far we are testing the first of these but not the second.

[pp-mo]

Update

Testing+ passing against various uses, in both 'index_by_dimension' and 'Slicer' forms
Todos

• Whatsnew
• Additional tests, e.g. Error modes
• Add a Howto entry
• ?? other docs mentions?

[ukmo-ccbunney]

Hey @pp-mo.

So, the Slicer class and index_by_dimensions utils are very useful (I made some other comments on #162 regarding the Slicer).

I really like the functionality of being able to slice the whole dataset, not just the individual variables. 🚀
This feels very much like the Xarray Dataset.[i]sel behaviour which makes it so much easier to work with compared to the netcdf4 library!

One minor thing: Could the Slicer class have a nice __str__ method to give some indication of the underlying NcData object it is associated with? Useful for interactive REPL use cases where you might want to check which object the Slicer is wrapped around.

[pp-mo]

Status update

WIP : Adopting solutions (still working on), as agreed -- see #162 (comment)

[pp-mo]

There's now a huge amount of stuff in here, as it acquired a few more-or-less related changes.
Hopefully all OK now.
Going to just merge, since other changes are waiting on it.