Free Your Tooltips

Feb 24, 2019

When I was reading a news website earlier today I had this nice user experience when I was hovering this chart:

I really like that you don’t have to follow the line chart to get the tooltip. Especially when you have a very thin line it can be hard in Tableau to hit the line to get the tooltip.

So, how can this be done in Tableau? I experimented a little bit with set actions, but the performance wasn’t good enough to come even close to the performance of my model. So, I finally ended up with this:

This technique has the same performance, however I had to get rid of the dot highlighting the corresponding value on the line chart. But nevertheless I think it can be useful in some limited use cases (having only one line and a free second axis).

How can it be done? Very easily:

1. Create a line chart (again: with only one line!)
2. Calculate the maximum value of the measure for each point. You can do this by using an LOD-expression or a table calc.
   I used this LOD-expression:
   

   

3. Bring this measure to the first axis (and your original measure to the second), create a dual axis and synchronize axes.
   

   

4. Select area from the marks card and set opacity to 0.
   

   

5. Match the tooltips for both axes.

That’s it!