Vega-lite: concatenate fields for a tooltip

Community Help
1

Hi all,
I have a very basic and I think stupid question.
I’m doing the first steps in observablehq and vega-lite.
I have forked a choropleth map notebook, and I have edit it a little:

  • I have changed the source data file
    • the former one does not have the state name
  • I have set the state name as tooltip.

How can I concatenate two fields name and delta and use the output as tooltip?

Thank you

2

hi @aborruso, you probably want to do this

      vl.tooltip([vl.fieldN('name'),vl.fieldQ('delta')])

you can see more examples here

1 Like
3

It works great thank you.

And what’s the way to have something like “state name, delta”, something like “Clark, 0.022”.

Best regards

4

It doesn’t look easy to me from reading the docs. Because they are objects being parsed to the tooltip each key-value pair is displayed in its own row.
Arrays will be shown in line, but I don’t know how it convert from the two objects into and array.

https://github.com/vega/vega-tooltip/blob/master/docs/creating_your_tooltip.md#step-4-define-your-tooltip-in-vega-or-vega-lite

I typed to be a bit hackery by using the forced ‘title’ to inject the name, but it’s an object and not the name.

vl.tooltip([{'field': 'delta','title':{'field': 'name'}}])
2 Likes