Deneb: Distribution curve on bar diagram

[Salle]

Hi, need some help on what I am doing wrong here.
The end-goal I wish to achive is a distribution curve combined with histogram.

I have been looking into the use of density in deneb but do not seem to get it right.

Code below

{
  "data": {"name": "dataset"},
  "layer": [
    {
      "description": "Histogram Bars",
      "mark": {
        "type": "bar",
        "color": "#7DA7D9",
        "tooltip": true
      },
      "encoding": {
        "x": {
          "bin": {"maxbins": 40},
          "field": "Diameter",
          "type": "quantitative",
          "scale": {
            "domain": [7.82, 7.87]
          },
          "axis": true,
          "title": ""
        },
        "y": {
          "aggregate": "count",
          "type": "quantitative",
          "axis": {"labels": false},
          "title": "Count"
        }
      }
    },
    {
      "description": "Histogram line",
      "transform": [
        {
          "density": "Diameter",
          "bandwidth": 0.3
        }
      ],
      "mark": {
        "type": "line",
        "color": "#931313",
        "strokeWidth": 2
      },
      "encoding": {
        "x": {
          "field": "value",
          "type": "quantitative"
        },
        "y": {
          "field": "density",
          "type": "quantitative"
        }
      }
    }
  ],
  "resolve": {
    "scale": {"y": "independent"}
  }
}

 Any ideas where the problem is?

[KerKol]

The code works for me on my own data. What happens when you set resolve to dependent?

And remove the domain scale?

[Salle]

@KerKol thanks for your suggestions but it did not help...

When I set to dependent it moves sligthly along the x-axis.
When I also remove the domain scale the bar streches out along the x-axis. In both cases the line is still not changing.

How about the "x": {"field" : "value"}... What is really inside "value", how can its content be verified or changed? 

I tried changing the bandwith since Diameter has several decimals and started to get some effect..

[KerKol]

sounds like you may have found the issue, the above curve looks about right.

You have the Y aggregated as a count for your bars, but perhaps not for your line. What happens if you adjust the aggregation?

[Salle · Accepted solution]

@KerKol, I adjusted the bandwith to match the standard deviation for the data sample used and got the following result.

---

@KerKol wrote:

sounds like you may have found the issue, the above curve looks about right.

You have the Y aggregated as a count for your bars, but perhaps not for your line. What happens if you adjust the aggregation?

---

For the y-axis of the bars I use the aggregate: "count" and for y-axis I use "field": "density".
I am curious about what you mean by "adjust the aggregation".

[dvmax]

Привет, мне так же интересна эта тема. Разместите полный код JSON, спасибо!