An experiment on treemap coloring, using color encoding for depth. Instead of regions, boundaries are colored. A categorical color scale is used to help find nodes at the same level in other parts of the map, while some padding between lines is used together with decreasing thickness to convey a sense of nesting.
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<title>Treemaps: boundary coloring</title>
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Modified http://d3js.org/d3.v3.min.js to a secure url
https://d3js.org/d3.v3.min.js