This tutorial is work in progress. If you want to help improving it, you're invited to fork it on Github

Creating Dorling Cartograms

It's a small step from a Bubble symbol map to a Dorling cartogram. At first you set up your base map layer.

map.addLayer('regions', {
    key: 'id'  // define which feature attribute holds the unique identifiers
});

It's up to you whether you want to show the geographical map or not. If you don't want to, just set the opacity to zero.

map.addLayer('regions', {
    key: 'id',
    styles: {
        opacity: 0
    }
});

Now add symbols of the type Bubble to your map.

symbols = map.addSymbols({
    type: kartograph.Bubble,
    data: ...
    location: function(d) {
        // return id of a map layer path to position
        // the symbol on its centroid
        return 'mylayer.' + d.pathId;
    },
    radius: function(d) {
        // define radius depending on some data, e.g. population
        return Math.sqrt(d.population / maxPop) * 30;
    }
});

Last thing you need to do is to run the dorlingLayout helper on your symbols:

kartograph.dorlingLayout(symbols);