Bubble size should scale area, not radius

Issue Summary

The size of bubbles seems to be applied directly as the diameter of the bubble. This means that doubling the size makes the bubble area quadruple, which is visually misleading if you are plotting a quantity, which I expect is the common case.

Steps to Reproduce

Select some data with a simple query like SELECT 1, 2, 50 UNION ALL SELECT 3, 4, 100, and plot it as a bubble chart. The bubble with size 100 will be four times the size of the bubble with size 50.

I would expect the radius to be set as the square root of the size, which would make the area and perceived size scale linearly with size. For example, this is how matplotlib does it.

Technical details:

• Redash Version: 8.0.0-beta+b27489
• Browser/OS:
• How did you install Redash: Helm chart

[susodapop]

This looks like a pretty simple change. Plotly supports the sizemode attribute for Bubble charts. The options are diameter and area.

Plotly doc: https://plot.ly/python/reference/#scatter-marker-sizemode

I changed it on a local build…

Diameter

Area

[kravets-levko]

@deecay It could be default for new charts, but migration should keep old behavior for all existing ones.