There are many ways to add interactive behaviors to hierarchical visualizations. If you have a very large tree, you may wish to zoom in to obtain details about the leaf nodes. You could implement a semantic zoom that expands the nodes as it zooms in. If you have a very complex hierarchy, with many links, you might use node and link highlighting to show a path between two nodes, or simply reveal the path between a particular node and the root. In a dynamic chart, you can also allow the user to drag nodes, add new nodes or remove existing ones.
This section describes three interactive behaviors you can add to a tree or dendogram: highlighting a path, using a subtree as the root and navigating up down a tree by expanding and collapsing nodes. Only relevant code fragments are shown, but the full code is available in the Interactive/ folder.
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