I have been trying to display two values simultaneously i.e. one absolute value displayed by bubble size (as with layer wizard: bubble) and one relative value displayed by color (as with layer wizard: chloropleth). (Adding to longitude and latitude these are four dimensions I want to visualize.) 

See <http://visage.co/data-visualization-101-bubble-charts/> for examples of bubble maps. 

I have now managed to combine the CSS for a bubble layer (marker-width) and the CSS for a chloropleth layer (marker-fill). However I fail to adjust the legend to indicate both dimensions. 

![choropleth + bubble visualization](https://i.stack.imgur.com/UWqE5.png)

Is there a way to do this with CartoDB? 

The thumbnail for Torque Cat in the Map layer wizward shows bubbles unequal in size and color, but I don't see how this could serve my purpose.