Two level selection chart, where the second level is dependent on the first level

[Ahasanatwork]

Hey,

I would like create an interactive line chart with two levels of selection, a main category and a sub-category.

The line chart would display data based on the first selection (main category) if the second selection (sub-category) has not yet been selected. Once the second selection has been selected, the line chart would display data based on the sub-category selection.

I would like the the two selections as a table above the line chart. The sub-category selection table would be reflective of the main category selection. In other words, the sub-category selection would be different for each main category selection.

Do you know if this is possible using Altair?

Asking as I haven't seen any examples with a two level selection chart, where the second level is dependent on the first level.

Many thanks!!