Making legends in Carto Builder reflect custom class breaks for graduated symbols?

Question

I am trying to build a map using Carto Builder that compares the average price of single family housing and multi-family housing by neighborhood. The data are offset centroids for each neighborhood, sized by the average cost of each type of housing. It is important that each data set use the same class breaks so that a visual comparison is possible. The data sets have different min/max values, so I manually set the class breaks for each using CartoCSS. However, the legend does not reflect the class breaks I set, and returns 'No data available' in the legend box. How do I fix this?

Here is the CartoCSS I am using:

#layer {
  marker-width: ramp([avg_sf], (6,12,18,24,30), 
(300000,400000,600000,800000,1000000));
  marker-fill: #e19c0c;
  marker-fill-opacity: 0.79;
  marker-allow-overlap: true;
  marker-line-width: 1;
  marker-line-color: #FFF;
  marker-line-opacity: 1;
}

And a screenshot showing the empty legend.

Answer 1

As explained in a previous related question, TurboCARTO was created to style layers to adapt to dynamic queries. As soon as you set the breaks values to static ones, the legend will not be generated. So if you know the structure of your layer dataset, we recommend using traditional CartoCSS conditionals as the following screenshot:

Then copy those breaks values in order to create a custom legend:

As you can see, my workaround is making a legend with colors instead of sizes. But because the color palette matches the size gradient, it can make the trick. Here is the resulting BUILDER public map.