force a legend when there is no corresponding data

Question

I'm hoping to get pointers for how to include an item in the legend despite the fact that it's not in the data---I tried to add it by way of sort, but that doesn't appear to work---editor link. In this example, I want "Not helpful" to show up in the legend, despite the fact that it was not present in any responses.

I understand that this is somewhat against the whole visual encodings concept, but I think the use case is valid.

Thanks for the help!

Answer 1

You can do this by specifying the scale domain:

"scale": {
  "domain": [
    "Extremely helpful",
    "Very helpful",
    "Somewhat helpful",
    "Not so helpful",
    "Not helpful"
  ]
}

The result looks like this (view in editor):