Browsing by Subject "Graph Layout"

Now showing 1 - 4 of 4

Open Access
Information flow and interconnections in computing: extensions and applications of Rent's rule
(Elsevier, 2004) Özaktaş, Haldun M.
Rent’s rule and related concepts of connectivity such as dimensionality, line-length distributions, and separators are discussed. Generalizations for systems for which the Rent exponent is not constant throughout the interconnection hierarchy are provided. The origin of Rent’s rule is stressed as resulting from the embedding of a high-dimensional information flow graph to two- or three-dimensional physical space. The applicability of these concepts to free-space optically interconnected systems is discussed. The role of Rent’s rule in fundamental studies of different interconnection media, including superconductors and optics, is briefly reviewed.
Open Access
A layout algorithm for graphs with overlapping clusters = Kesişen kümelenmiş çizgeler için bir yerleştirme algoritması
(2014) Cengiz, Can Çağdaş
Graphs are often used for visualizing relational data such as social or biological networks. Numerous methods have been proposed for automatic layout of simple graphs. However, simple graphs are usually insufficient in displaying relational information, since relational information is often clustered. Clustering models traditionally assume that each data point belongs to one and only one cluster; however, in complex networks, these clusters often overlap. For effective visualization of clustered graphs, the nodes in the same cluster should be placed together, respecting general graph drawing criteria such as avoiding node-node overlaps, minimizing edge crossings, and minimizing the total drawing area. Clustered graph layout problem becomes even more challenging when cluster overlaps are allowed. Here, we present a new algorithm for automatic layout of graphs with overlapping clusters based on force directed layout approach. The graph is first divided into zones according to clusters and their intersections, and new additional forces are introduced to the traditional spring embedder algorithm to keep nodes in the same cluster together, trying to keep neighboring nodes in separate clusters at a safe distance. Spring constants had to be fine-tuned to achieve a fast and effective layout operation. The algorithm was implemented and validated within a new layout style named Cluster Layout in the layout module of ChiEd visualization tool.
Open Access
Polygon packing approach to disconnected graph layout
(2003) Başköy, Cihad
Graph layout has become an important area of research in Computer Science for the last couple of decades. There is a wide range of applications for graph layout including data structures, databases, software engineering, VLSI technology, electrical engineering, production planning, chemistry, and biology. Most layout algorithms assume the graph to be connected. However, most graphs are disconnected and a method for putting the disconnected graph objects together is needed. Two-dimensional packing algorithms have wide area of application such as in the steel and textile industry. In steel industry, problems frequently occur when the need to stamp polygonal figures from a rectangular board arises. In the textile industry, similar problems exist. The aim is same: to maximize the use of the contiguous remainder of the board. Recently, two-dimensional packing has also been used in disconnected graph layout yielding algorithms that ‘tile’ the disconnected graph objects, which are represented by rectangles. These algorithms are also required to respect the specified aspect ratio for the final layout. A more recent approach to disconnected graph layout has been the use of polyominoes for representing the graph objects resulting in more accurate packings at the cost of increased execution times. In this thesis, we use polygons for a more accurate representation of graph objects and present new algorithms for disconnected graph layout. Specifically, we apply the No-Fit Polygon approach in twodimensional packing to disconnected graph layout. We present and analyze the graph layouts resulting from our new approach and contrast the new approach with previous ones.
Open Access
Two-dimensional packing algorithms for layout of disconnected graphs
(Elsevier, 2002) Dogrusoz, U.
We present and contrast several efficient two-dimensional packing algorithms for specified aspect ratio. These near-linear algorithms are based on strip packing, tiling, and alternate-bisection methodologies and can be used in the layout of disconnected objects in graph visualization. The parameters that affect the performance of these algorithms as well as the circumstances under which they perform well are analyzed. © 2002 Elsevier Science Inc. All rights reserved.