Example of a line chart with a label annotating the final value

[palewire]

Fixes #2622

It should look like this:

The example was drawn from the Vega-Lite docs

[joelostblom]

Thanks for this contribution! I recently fixed the CI tests, could you rebase this on the main branch so that we can see that all the tests are passing here before merging?

[palewire]

I believe I've done that.

[mattijn]

Interesting approach! I was not aware of argmax in this context.

While I like your approach, there exist a shorthand for

x=alt.X('date:T', aggregate='max')

namely

x=alt.X('max(date):T')

And, while shorter in your example, this line:

y=alt.Y('price:Q', aggregate={'argmax': 'date'})

could be written in the Altair approach as

y=alt.Y('price:Q', aggregate=alt.ArgmaxDef(argmax='date'))

since there is no shorthand for this (that I'm aware of).

All in all, the possible changes won't make it more readable..
What you think @joelostblom?

Maybe we could create an issue as well to expand the Altair docs for aggregation as well with more info from vl-aggregate-ops and vl-aggregate-argmax.

[palewire]

I'm fine with those edits if it's what you'd prefer to showcase.

[palewire]

I made the changes for you.

[mattijn]

Thanks!