The Hilbert map presented in the previous example is here improved by aggregating the quads belonging to the same class (The Clipper library has been used for this purpose). The map results to be ligther than the previous one, since a single SVG path is used for representing a class instead of a set of squares.
Modified http://d3js.org/d3.v3.min.js to a secure url
Modified http://jsclipper.sourceforge.net/6.1.3.1/clipper.js to a secure url
https://d3js.org/d3.v3.min.js
https://jsclipper.sourceforge.net/6.1.3.1/clipper.js