Specify custom sorting on split-by/group-by entries in datagrid

[ja-b]

Support Question

How do I specify custom sorting on split-by/group-by entries in the perspective-viewer-datagrid?

Say I have the following

Where I'd like to sort the 18M, 1Y, 2Y etc. columns differently than the default string-sorting method built-in (one thats aware of the spans they represent). I tried looking for an example of this but couldn't find anything.

I'm interacting with this via Panel, which uses the Perspective Python-API under the hood.

[texodus]

You need a column sort e.g. "col desc" or the 3rd/4th click state for the sort icon, as well as a category aggregate e.g. dominant or unique. You can provide this sort order in your data set (e.g. tenor sort order) or you can calculate it in an expression column using the order() function, it would look something like this:

viewer.restore({ 
    sort: [["tenor_sort", "col desc"], ...],
    aggregate: {"tenor_sort": "dominant" ...},
    expressions: [`//tenor_sort\norder("Tenor", '6m', '18m', .... )`, ...],
   ....
})

... or as an expression in the UI (note in both examples " vs ' for column names vs string values)

order("tenor", '6m', '18m', ... )