I would like to make the CartoDB heatmap use weighted values from a column in the dataset. I tried to find the option in the wizards and the docs but I couldn't find anything. Is there a way to do that?

  • 1
    Heatmaps are a variation of Torque maps, maybe you could change the torque-aggregation-function of the Heatmap in order to get the effect that you want. You can find more information about how the Torque spatial aggregation works here:github.com/CartoDB/torque/wiki/How-spatial-aggregation-works – oriolbx Feb 11 '16 at 9:49
  • @oriolbx that comment deserves to be in an answer, not in the comments! :-) – iriberri Feb 14 '16 at 10:53

As @oriolbx suggested in the comments it is possible through the torque-aggregation-function. You can change the standard heatmap CartoCSS like this:

/** torque_heat visualization */

Map {

  image-filters: colorize-alpha(blue, cyan, lightgreen, yellow , orange, red);
  marker-file: url(http://s3.amazonaws.com/com.cartodb.assets.static/alphamarker.png);
  [value < 1] {marker-fill-opacity: 0.05;}
  [value < 10] {marker-fill-opacity: 0.1;}
  [value < 100] {marker-fill-opacity: 0.2;}
  [value < 1000] {marker-fill-opacity: 0.4;}
  [value < 10000] {marker-fill-opacity: 0.6;}
  [value < 100000] {marker-fill-opacity: 0.8;}
  [value >= 100000] {marker-fill-opacity: 1.0;}
  marker-width: 7;

The only differences are the -torque-aggregation-function, for which I used my weight column, and the marker-fill-opacity, that has to be modified to take into account the output value of the torque aggregation function, stored in the value variable.

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