I have a Vega visualization that displays data in a table built using rect and text marks:
I can define the x_step signal to define the width in pixel of each column (but with the same value for all columns). Now, since my first and third column have much smaller text content than the second, I'd like to use one column width for the second column and another for the first and third. I cannot find a way to do it since it seems I cannot use datum in signals.
Please note that I want to change the axis width, not only the rect width.
Also, I need to use Vega v5.
Here's my JSON spec:
{
"$schema": "https://vega.github.io/schema/vega/v5.json",
"autosize": "none",
"background": "white",
"padding": {"top": 60},
"style": "cell",
"data": [
{
"name": "source_0",
"values": [
{
"date": "2025-03-24T12:00:00+0100",
"key": "2210"
},
{
"date": "2025-03-24T13:00:00+0100",
"key": "2211"
},
{
"date": "2025-03-24T12:30:00+0100",
"key": "2212"
},
{
"date": "2025-03-24T12:50:00+0100",
"key": "2213"
}
],
"transform": [
{
"type": "formula",
"expr": "(now() - time(datum.date)) / 1000",
"as": "delta_sec"
},
{
"type": "formula",
"expr": "if(datum.delta_sec >= 31536000, floor(datum.delta_sec / 31536000) + \" year\", if(datum.delta_sec >= 2592000, floor(datum.delta_sec / 2592000) + \" month\", if(datum.delta_sec >= 86400, floor(datum.delta_sec / 86400) + \" day\", if(datum.delta_sec >= 3600, floor(datum.delta_sec / 3600) + \" hour\", if(datum.delta_sec >= 60, floor(datum.delta_sec / 60) + \" minute\", floor(datum.delta_sec) + \" second\")))))",
"as": "delta_str"
},
{
"type": "formula",
"expr": "if(parseInt(split(datum.delta_str, \" \", 1)[0]) > 1, datum.delta_str + \"s\", datum.delta_str)",
"as": "Ago"
},
{"type": "formula", "expr": "datum.delta_sec < 3600", "as": "color"},
{
"type": "window",
"params": [null],
"as": ["row_num"],
"ops": ["row_number"],
"fields": [null],
"sort": {"field": [], "order": []}
},
{"type": "formula", "expr": "datum.key", "as": "Key"},
{
"type": "formula",
"expr": "datum.date",
"as": "Date"
},
{
"type": "fold",
"fields": ["Key", "Date", "Ago"],
"as": ["key", "value"]
},
{
"type": "formula",
"expr": "datum[\"key\"]===\"Key\" ? 0 : datum[\"key\"]===\"Date\" ? 1 : datum[\"key\"]===\"Ago\" ? 2 : 3",
"as": "x_key_sort_index"
}
]
}
],
"signals": [
{"name": "x_step", "value": 250},
{"name": "width", "update": "containerSize()[0]"},
{"name": "y_step", "value": 20},
{"name": "height", "update": "containerSize()[1]"}
],
"marks": [
{
"name": "layer_0_marks",
"type": "rect",
"style": ["rect"],
"from": {"data": "source_0"},
"encode": {
"update": {
"fill": {"scale": "color", "field": "color"},
"description": {
"signal": "\"row_num: \" + (isValid(datum[\"row_num\"]) ? datum[\"row_num\"] : \"\"+datum[\"row_num\"]) + \"; key: \" + (isValid(datum[\"key\"]) ? datum[\"key\"] : \"\"+datum[\"key\"]) + \"; color: \" + (isValid(datum[\"color\"]) ? datum[\"color\"] : \"\"+datum[\"color\"])"
},
"x": {"scale": "x", "field": "key"},
"width": {"scale": "x", "band": 1},
"y": {"scale": "y", "field": "row_num"},
"height": {"scale": "y", "band": 1}
}
}
},
{
"name": "layer_1_marks",
"type": "text",
"style": ["text"],
"from": {"data": "source_0"},
"encode": {
"update": {
"fontSize": {"value": 12},
"fill": {"value": "#eeeeee"},
"description": {
"signal": "\"row_num: \" + (isValid(datum[\"row_num\"]) ? datum[\"row_num\"] : \"\"+datum[\"row_num\"]) + \"; key: \" + (isValid(datum[\"key\"]) ? datum[\"key\"] : \"\"+datum[\"key\"]) + \"; value: \" + (isValid(datum[\"value\"]) ? datum[\"value\"] : \"\"+datum[\"value\"])"
},
"x": {"scale": "x", "field": "key", "band": 0.5},
"y": {"scale": "y", "field": "row_num", "band": 0.5},
"text": {
"signal": "isValid(datum[\"value\"]) ? datum[\"value\"] : \"\"+datum[\"value\"]"
},
"align": {"value": "center"},
"baseline": {"value": "middle"}
}
}
}
],
"scales": [
{
"name": "x",
"type": "band",
"domain": {
"data": "source_0",
"field": "key",
"sort": {"op": "min", "field": "x_key_sort_index"}
},
"range": {"step": {"signal": "x_step"}},
"paddingInner": 0,
"paddingOuter": 0
},
{
"name": "y",
"type": "band",
"domain": {"data": "source_0", "field": "row_num", "sort": true},
"range": {"step": {"signal": "y_step"}},
"paddingInner": 0,
"paddingOuter": 0
},
{
"name": "color",
"type": "ordinal",
"domain": ["true", "false"],
"range": ["#19aa6e", "#788291"]
}
],
"axes": [
{
"scale": "x",
"orient": "top",
"gridScale": "y",
"grid": true,
"domain": false,
"labels": false,
"aria": false,
"maxExtent": 0,
"minExtent": 0,
"ticks": false,
"zindex": 1
},
{
"scale": "x",
"orient": "top",
"grid": false,
"labelAngle": 0,
"labelFontSize": 15,
"ticks": false,
"labelBaseline": "bottom",
"zindex": 1
}
],
"legends": [
{
"labelFontSize": 12,
"labelLimit": 300,
"orient": "top",
"fill": "color",
"direction": "horizontal",
"symbolType": "square",
"encode": {
"labels": {
"update": {
"text": {
"signal": "if(datum.value == 'true', 'Less than 60 min ago', 'More than 60 min ago')"
}
}
}
}
}
],
"config": {"axis": {"grid": true, "tickBand": "extent"}}
}
