treecut.js

treecut.js automatically adjusts the level of abstraction of treemaps as a function of display size.

The abstraction is determined by a tree cut, which is essentially a boundary between the visible and hidden parts of the tree.

The tree cut selection algorithm is based on the Minimum Description Length principle. To reduce clutter when space is scarce, it sets the cut above subtrees that have more uniform scores. This behaviour has the effect of exposing subtrees that contain nodes with a dramatically disproportionate score (outliers) while collapsing regular subtrees. Conversely, with more space, the algorithm tends to select lower cuts, allowing more nodes to be displayed.

You can read the full technical details in our research paper.

Usage

With d3.hierarchy

Get your tree ready with d3.hierarchy as usual:

var tree =  d3.hierarchy(data);
    .sum(function(d) { return d.children ? d.value : 0; })
    .sort(function(a,b){ return b.value - a.value; });

Then let treecut.js adorn it with its own attributes:

var treecut = vialab.treecut;
treecut.hierarchy()
    .adornD3(tree);

Extract the cut.

var cut = treecut.treemap()
    .findcut(tree, 800*600); // 800*600 is the display area, in pixels

findcut returns an array of nodes that belong to the cut. You can mark the nodes under the cut as invisible before drawing the treemap:

cut.forEach(function(d){
    d.descendants().forEach(function(o,i){
      if (i==0) return;
      o.visible = false;
    });
});

Example

Demos

Load the pages on windows of different size to see how the treemap adapts.

MeSH - Medical Subject Headings

MeSH is a hierarchy of 56,327 categories used to tag PubMed publications. The size of a category encodes the number of papers contained in it. For each category A, a child named (A) represents the number of papers tagged directly with A.

Link: http://vialab.science.uoit.ca/mesh/

You can compare the view above with the unabstracted MeSH treemap.

DMOZ (Directory Mozilla)

DMOZ is a hierarchical web directory of nearly half a million categories.

Link: http://vialab.science.uoit.ca/dmoz/

Slides (VIS 16 Talk)

Link: https://vialab.ca/treecut/slides

Tip: Use keys W, D, S and A to interact with slides 9 and 12. On slide 12 you can also click on nodes to anchor the tree cut.

Citation

R. Veras; C. Collins, "Optimizing Hierarchical Visualizations with the Minimum Description Length Principle," in IEEE Transactions on Visualization and Computer Graphics , vol.23, no.1, pp.631-640.

@Article{Veras2017,
Author = { Rafael Veras and Christopher Collins },
Journal= {IEEE Transactions on Visualization and Computer Graphics },
Title= { Optimizing Hierarchical Visualizations with the Minimum Description Length Principle },
Year= {2017},
Volume = { 23 },
Number = { 1 },
Pages= { 631--640},
Keywords = { Hierarchy data, data aggregation, multiscale visualization, tree cut, antichain },
DOI = { 10.1109/TVCG.2016.2598591 },
ISSN = { 1077-2626 },
Month = jan,
}