TreeAndLeaf: A graph layout strategy for binary trees with focus on the leaves

Milena A Cardoso, Luis E A Rizzardi, Leonardo W Kume, Sheyla Trefflich, Clarice Groeneveld, Mauro A A Castro

Abstract

The TreeAndLeaf package combines tree and force-directed layout algorithms for drawing binary trees, aiming to represent multiple layers of information onto the leaves.

Package

TreeAndLeaf 1.18.0

Contents

1 Overview

A dendrogram diagram displays binary trees focused on representing hierarchical relations between the tree elements. A dendrogram contains nodes, branches (edges), a root, and leaves (Figure 1A). The root is where the branches and nodes come from, indicating the direction to the leaves, i.e., the terminal nodes.

Most of the space of a dendrogram layout is used to arrange branches and inner nodes, with limited space to the leaves. For large dendrograms, the leaf labels are often squeezed to fit into small slots. Therefore, a dendrogram may not provide the best layout when the information to be displayed should highlight the leaves.

The TreeAndLeaf package aims to improve the visualization of the dendrogram leaves by combining tree and force-directed layout algorithms, shifting the focus of analysis to the leaves (Figure 1B). The package’s workflow is summarized in Figure 1C.