Reference ncdata in docs.

[pp-mo]

This is just an attempt to augment the existing links to Iris and usage, to include reference to ncdata.
I could add more coverage of the why and how, but I don't think it is really wanted in xarray docs, so a link should be enough.

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[dcherian]

Nice! Is this the preferred way to convert between Iris & Xarray now? If so, we'd be happy to delete the existing methods, I am not sure anyone uses them anyway.

[pp-mo]

Note : you might argue that ncdata should allow to retire DataArray.to_iris / from_iris, but I really don't think the world is ready for that !
There are arguments on both sides:

• I feel like 'to_iris' and 'from_iris' are embedding iris concepts within xarray, which doesn't seem like a great idea.
• they don't handle all aspects of CF translation : so, a significant part of the motivation for ncdata was to enable "correct" translation via iris loading code for CF Conventions management, since to_iris can obviously only handle some parts of that.

..but..

• to_iris and from_iris are obviously useful legacy, and easy to use
• for simple cases, they avoid ncdata as an additional code dependency (though they do need Iris itself)

[pp-mo]

Nice! Is this the preferred way to convert between Iris & Xarray now? If so, we'd be happy to delete the existing methods, I am not sure anyone uses them anyway.

Oh my additional remarks crossed with yours!

The answer very much depends on what you think.
Practically, right now, I think ncdata can handle "almost" anything, but it is not yet supporting 'string' type variables which has suddenly emerged as a bit of a problem. I should be looking into that shortly.

[pp-mo]

I am not sure anyone uses them anyway.

I'd really need to defer to your understanding of that.
In Iris, we always find those questions really hard! (but we probably have a much more conservative user base)

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