Visualizing Hierarchical Data

Synonyms

Hierarchical graph layout; Hierarchical visualization; Information visualization on hierarchies; Multilevel visualization;Tree drawing; Visualizing trees

Definition

Hierarchical data is a data that can be arranged in the form of a tree. Each item of data defines a node in the tree, and each node may have a collection of other nodes as child nodes. The relationship between the parent nodes and the child nodes forms a tree network. The formal definition of a tree is that the graph formed by the nodes and edges (defined between parent and child node) is both connected and contains no cycles. The following properties of a tree are of more practical use from the point of view of displaying visualizations:

• One node, called the root node, has no parent.

• All other nodes have exactly one parent.

• Nodes with no children are termed leaf nodes. Nodes with children are termed interior nodes.

• For all nodes in a tree, there is a single unique path up the tree going from parent to parent’s...