Susan Smith has worked as an editor and writer in the technology industry for over 16 years. As an editor she has been responsible for the launch of a number of technology trade publications, both in print and online. Currently, Susan is the Editor of GISCafe and AECCafe, as well as those sites’ … More »
512 paths to the White House with a binary election tree
November 5th, 2012 by Susan Smith
The Project: 512 Paths to the White House by Mike Bostock, The New York Times
This is a behind-the-scenes look at the creation of a visualization by The New York Times:
“The space of electoral college calculators is fairly well-trodden, so at first it seemed hard to do something new. The big problem here is the combinatorial explosion (2^n): even if you consider only nine states, you have 512 possible outcomes! So, you don’t offer much insight by simply enumerating outcomes or allowing undirected exploration. The challenge is to preserve minute details (micro) while providing an effective visual summary (macro).
We settled on a binary tree early on, but it wasn’t until Shan had the idea of collapsing parts of the tree into “decision” nodes that the design clicked. By pruning subtrees below the 270-vote threshold, you reduce the complexity substantially. More importantly, you get a much faster sense of what matters: who wins! And from there it was “just” a matter of implementation and refinement.
The nodes are positioned using the Reingold-Tilford “tidy” algorithm, as implemented by D3’s tree layout. The static layout was therefore surprisingly simple (because of the existing D3 layout); the binary tree is computed recursively by summing the electoral votes for each path.”
The New York Times
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