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Tree Navigator - A concept for navigation in big trees

IP.com Disclosure Number: IPCOM000015154D
Original Publication Date: 2001-Aug-13
Included in the Prior Art Database: 2003-Jun-20
Document File: 4 page(s) / 135K

Publishing Venue

IBM

Abstract

Tree Navigator A concept for navigation in big trees Motivation In current applications information is often structured and visualized in trees. Those trees have often a lot of nodes. As a consequence closely related nodes such as sibling nodes are displayed far away from each other if their sub trees are expanded. Additionally the nodes themselves are sometimes displayed on a relatively big area on the screen (i.e. pie charts, tables, (editable) text boxes, etc. are used as tree nodes). Therefore you often have the following situation. Deep tree structures have to be displayed, but there is only room for the representation of a few nodes on the screen.

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Tree Navigator - A concept for navigation in big trees

Motivation

    In current applications information is often structured and visualized in trees. Those trees have often a lot of nodes. As a consequence closely related nodes - such as sibling nodes - are displayed far away from each other if their sub trees are expanded. Additionally the nodes themselves are sometimes displayed on a relatively big area on the screen (i.e. pie charts, tables, (editable) text boxes, etc. are used as tree nodes).

    Therefore you often have the following situation. Deep tree structures have to be displayed, but there is only room for the representation of a few nodes on the screen.

    This problem can be solved in different ways. Some applications use so called tree maps to display the tree structure in a separate window, others provide a zoom function to switch between an overview on the tree structure and a view on the detailed information provided by the tree nodes. Another idea for a solution of the described problem is given in this article.

To describe the functionality of the "Tree Navigator" concept we need the following

Definitions

terms:
Let N(T) be the set of all nodes in a tree structure T. A root node of T is a node without parent nodes.In thefollowingsections we will consider a tree with one unique root node.

    For any node NN(T) define Path(N) as the shortest path from the trees root node up to N (including N) and P(N) the parent node of N.

Let

C(N) := { C Ν(Τ) : Ν

= P(C)}

be the set of N's child nodes and

S(N) := { S Ν(Τ) : P(S) = P(N)}

the set of N's sibling nodes (including N). Now we define the environment of N with radius i ∈{0, 1, 2, . . . } recursively as follows:

E1(N) := P(N) S(N) C(N)

Ei(N) := NEi-1E1 (N)

Examples:

1

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Figure 1: E1(N), Environment of node N (3.2) with radius 1.

Figure 2: E2(N), Environment of node N (3.2) with radius 2.

Based on these definitions we construct the displayed navigator tree Di(N) with radius i as:

Di(N) := Path(N) Ei(N).

Example:

Figure 3: D1(N)

    The navigator tree of a node now was defined as a set of "interesting" nodes, if the user selects a node. The definition might become clear with the following examples for concrete applications:

    File trees: P(N) is the file path, S(N) is the set of folders in that pathand C(N) shows sub folders and files of selected folder.

    Decision trees: A node N represents a decision, which is made by entering N on the decision path P(N). S(N) describes alternative decisions and C(N) shows all possible decisions in the next step.

    XML Editors could use trees to structure their data in a similar way. The radius i of the environment can be interpreted as the number of steps which are allowed for walking away from N through the tree without leaving the set Ei...