Advanced tooltip customization

[sfc-gh-cheliu]

Hi there,

I want to contribute to the altair repo such that I can achieve:

1. Filter out/hide null/nan values in tooltip
2. Sort the values in tooltip

Not sure whether this is the feasible approach, but I think if alt.Chart can be built based on a dictionary, then I somehow sort and filter out some keys/values. Could you please give me some pointers where I can start?

Thanks

---

Please follow these steps to make it more efficient to respond to your feature request.

• [x] Since Altair is a Python wrapper around the Vega-Lite visualization grammar, most feature requests should be reported directly to Vega-Lite. You can click the Action Button of your Altair chart and "Open in Vega Editor" to create a reproducible Vega-Lite example.
• [x] Search for duplicate issues.
• [x] Describe the feature's goal, motivating use cases, and its expected behavior.