Why column facet in Vega Lite not working properly with layer? - vega

Question

I'm trying to create 3 column plot and it works when there's no layer.
But when I add the layer - 3 columns get merged into one plot (open in editor).
How to make it to be separated into 3 columns by the duration field?
CODE
For the plot with the full data please use editor link above.
{
"encoding": {
"column": { "field": "duration", "type": "nominal" },
"x": { "field": "bin_i", "type": "ordinal" }
},
"layer": [
{
"mark": { "type": "bar", "size": 2 },
"encoding": {
"y": { "field": "min", "type": "quantitative" },
"y2": { "field": "max", "type": "quantitative" }
}
},
{
"mark": { "type": "tick" },
"encoding": {
"y": { "field": "mean", "type": "quantitative" }
}
}
],
"data": {
"values": [
{
"bin_i": 1,
"duration": 1,
"max": 1.9642835793718165,
"mean": 1.0781367168962268,
"min": 0.3111818864927448
},
...
]
}
}

Answer 1

A layered chart does not accept a faceted encoding. If you want to facet a layered chart, you should use the facet operator rather than a facet encoding.
For your example, it would look like this (Vega Editor):
{
"facet": {"column": {"field": "duration", "type": "nominal"}},
"spec": {
"encoding": {
"x": {"field": "bin_i", "type": "ordinal"}
},
"layer": [
{
"mark": {"type": "bar", "size": 2},
"encoding": {
"y": {"field": "min", "type": "quantitative"},
"y2": {"field": "max"}
}
},
{
"mark": {"type": "tick"},
"encoding": {
"y": {"field": "mean", "type": "quantitative"}
}
}
]
},
"data": {
"values": [
{
"bin_i": 1,
"duration": 1,
"max": 1.9642835793718165,
"mean": 1.0781367168962268,
"min": 0.3111818864927448
},
...
]
}
}