6. The method defined in claim 1 wherein adapting the plurality of visualizations to an available display width comprises evaluating a plurality of subtrees by at least two tree functionals and selecting a subtree that has a preselected ratio among the tree functional values subject to a size constraint on subtree visualization.
6. The method defined in claim 1 wherein adapting the plurality of visualizations to an available display width comprises evaluating a plurality of subtrees by at least two tree functionals and selecting a subtree that has a preselected ratio among the tree functional values subject to a size constraint on subtree visualization. 7. The method defined in claim 6 wherein the preselected ratio of tree functional values comprises a smallest ratio of distortion versus the required visualization area of all subtrees with a specified root node.