`Fixed` interaction with selection defaults

[declann]

I'm setting selection defaults through menu inputs that have values set.

Fixed scale domain setting I'm using behaves as advertised in that the scale domain doesn't change on subsequent data updates.

But, I expected the domain calculation to include all data.

It's filtered to the default selection however. It might be ambiguous but this seems like a bug to me?

To reproduce:

1. Go to specs/yaml/sorted-bars.yaml, which has a default selection for acquatics
2. add xDomain: Fixed

Here is a gif of the result:

Screencast.from.2024-10-28.20-24-50.webm

The domain is fixed but whenever I select All, then data is truncated.

---

When I fix the domain with no default selection I see a fuller representation:

Should Fixed give this range, independent of the default selection?

[jheer]

Hi @declann, unfortunately you're running up against a current limitation of vgplot. The Fixed domain setting fixes the domain based on the first values it sees. For many mark types we hand queried data over to Observable Plot and then use the domain settings it chooses based on the chart attributes.

To get the "full" domain we need to get the full range of values from the database. Fortunately, this is something you can also do yourself if you're using the JavaScript API. Though more cumbersome, you can query DuckDB (e.g., using coordinator.query()) to get value ranges and determine a hard-wired domain of your own to pass into your chart spec.

For more automatic support (inc. from YAML/JSON specs), we'd need to extend vgplot to perform this logic behind the scenes. I'll interpret this issue as a feature request for this support.

[declann]

JS API workaround work for me, thanks Jeff and thanks for the explanation.