|
Abstract : |
This paper is aimed at the exploratory visualization of networks where there is a strength or weight associated with each link, and makes use of any hierarchy present on the nodes to aid the investigation of large networks. It describes a method of placing nodes on the plane that gives meaning to their relative positions. The paper discusses how linking and interaction principles aid the user in the exploration. Two examples are given; one of electronic mail communication over eight months within a department, another concerned with changes to a large section of a computer program. I. THE PROBLEM It has almost become a clich to start a paper with the observation that the amount of data in the world is growing rapidly, and that current efforts to extract useful information from data lag far behind the ability to create data. However the clich is true, and no less so in the field of network analysis and visualization than in any other. In many areas, scientists are realizing that the tools they have been using are limited in utility when applied to large, information-rich networks. Not only are networks of interest large in terms of size (as measured by number of nodes or links between nodes), but also in terms of the data collected for each node or link. The ability to examine statistics on the nodes and relate them to the network is of crucial importance. Examples of areas in which the analysis of large networks is important include: i. Trade flows. The concern in this area is monitoring imports and exports of various products at several levels; international, interstate and local. Besides examining many types of trade goods, there is also strong interest in spotting temporal patterns. ii. Communication networks. This is an important and wide category, covering not only telecommunication networks, but also electronic mail (email), financial transaction, ATM/bank data transferal and other data distribution networks., |
