Add possibility for vconcat => columns => expression

[apb-reports]

I need the ability to have many charts wrap automatically with the use of vconcat and facet. To get this working I need ability to set vconcat columns with an expression.
I can get page width like this:

"params": [
{ "name": "_width", "value": "0", "on": [ { "events": { "source": "window", "type": "resize" }, "update": "windowSize()[0]" }]},
],

Then get width and column width like this:

"transform": [
{"calculate": "windowSize()[0]", "as": "windowWidthTemp"},
{"calculate": "_width", "as": "windowWidth"},
{"calculate": "datum.windowWidth == 0 ? datum.windowWidthTemp : datum.windowWidth", "as": "windowWidthFinal"},
{"calculate": "datum.windowWidthFinal <= 500 ? 1 : datum.windowWidthFinal <= 1000 ? 2 : datum.windowWidthFinal <= 1500 ? 3 : datum.windowWidthFinal <= 2000 ? 4 : 5", "as": "chartColumns"}
]

To wrap things up I need this to work:

"vconcat": [
    {
      "columns": {"expr": "datum.chartColumns"},

Thanks in advance.

My stackoverflow example:
https://stackoverflow.com/questions/78186820/vega-lite-facet-chart-spread-over-columns-and-rows

• I checked for duplicate issues.