Incorrect axis position for grouped marks - vega

Question

I'd like to group axes and marks together within a group mark, as I'd like a bar chart to be one of several onto the data. However, when I do so the x axis moved from the bottom to the top of the bar chart. Here's an example:
{
"$schema": "https://vega.github.io/schema/vega/v4.json",
"width": 400,
"height": 200,
"padding": 5,
"data": [
{
"name": "cars",
"format": {
"type": "json",
"parse": {
"year": "date"
}
},
"url": "https://vega.github.io/vega-datasets/data/cars.json",
"transform": [
{
"type": "aggregate",
"groupby": [
"Origin"
],
"as": [
"num_records"
]
}
]
}
],
"scales": [
{
"name": "x",
"type": "band",
"domain": {
"data": "cars",
"field": "Origin"
},
"range": "width",
"padding": 0.05
},
{
"name": "y",
"type": "linear",
"domain": {
"data": "cars",
"field": "num_records"
},
"range": "height",
"nice": true
}
],
"marks": [
{
"type": "group",
"axes": [
{
"orient": "bottom",
"scale": "x"
},
{
"orient": "left",
"scale": "y"
}
],
"marks": [
{
"type": "rect",
"from": {
"data": "cars"
},
"encode": {
"enter": {
"x": {
"scale": "x",
"field": "Origin"
},
"width": {
"scale": "x",
"band": 1
},
"y": {
"scale": "y",
"field": "num_records"
},
"y2": {
"scale": "y",
"value": 0
}
}
}
}
]
}
]
}
The Group Mark documentation suggests that groups support such nested visualisation specifications. What am I doing wrong?

Answer 1

What I was doing wrong was not encoding the width and height of the group mark. Here's my revised example:
{
"$schema": "https://vega.github.io/schema/vega/v4.json",
"width": 400,
"height": 200,
"padding": 5,
"data": [
{
"name": "cars",
"format": {
"type": "json",
"parse": {
"year": "date"
}
},
"url": "https://vega.github.io/vega-datasets/data/cars.json",
"transform": [
{
"type": "aggregate",
"groupby": [
"Origin"
],
"as": [
"num_records"
]
}
]
}
],
"scales": [
{
"name": "x",
"type": "band",
"domain": {
"data": "cars",
"field": "Origin"
},
"range": "width",
"padding": 0.05
},
{
"name": "y",
"type": "linear",
"domain": {
"data": "cars",
"field": "num_records"
},
"range": "height",
"nice": true
}
],
"marks": [
{
"type": "group",
"axes": [
{
"orient": "bottom",
"scale": "x"
},
{
"orient": "left",
"scale": "y"
}
],
"encode": {
"enter": {
"width": {
"signal": "width"
},
"height": {
"signal": "height"
}
}
},
"marks": [
{
"type": "rect",
"from": {
"data": "cars"
},
"encode": {
"enter": {
"x": {
"scale": "x",
"field": "Origin"
},
"width": {
"scale": "x",
"band": 1
},
"y": {
"scale": "y",
"field": "num_records"
},
"y2": {
"scale": "y",
"value": 0
}
}
}
}
]
}
]
}