Browsing by Subject "Graph drawing"

Now showing 1 - 6 of 6

Open Access
CiSE: a circular spring embedder layout algorithm
(Institute of Electrical and Electronics Engineers, 2013) Dogrusoz, U.; Belviranli, M. E.; Dilek, A.
We present a new algorithm for automatic layout of clustered graphs using a circular style. The algorithm tries to determine optimal location and orientation of individual clusters intrinsically within a modified spring embedder. Heuristics such as reversal of the order of nodes in a cluster and swap of neighboring node pairs in the same cluster are employed intermittently to further relax the spring embedder system, resulting in reduced inter-cluster edge crossings. Unlike other algorithms generating circular drawings, our algorithm does not require the quotient graph to be acyclic, nor does it sacrifice the edge crossing number of individual clusters to improve respective positioning of the clusters. Moreover, it reduces the total area required by a cluster by using the space inside the associated circle. Experimental results show that the execution time and quality of the produced drawings with respect to commonly accepted layout criteria are quite satisfactory, surpassing previous algorithms. The algorithm has also been successfully implemented and made publicly available as part of a compound and clustered graph editing and layout tool named Chisio. © 1995-2012 IEEE.
Open Access
A compound graph layout algorithm with support for ports
(2020-10) Okka, Alihan
Information visualization is a eld of study that aims to represent abstract data in an aesthetically pleasing and easy to comprehend visual manner. Various approaches and standards have been created to reinforce the discovery of unstructured insights that are limited to human cognition via visual depictions. Complex systems and processes are often modelled as graphs since it would be di cult to describe in text. A type of visualization, graph drawing, addresses the notion of creating geometric representations of graphs. There are plentiful research directed to designing automatic layout algorithms for visualizing graphs. Nevertheless, a limited number of studies utilize ports, which are dedicated connection points on the locations where edge ends link to their incident nodes. We propose a new automatic layout algorithm named CoSEP supporting port constraints on compound nodes used for nested levels of abstractions in data. The CoSEP algorithm is based on a force-directed algorithm, Compound Spring Embedder (CoSE). Additional heuristics and force types are introduced on top of existing physical model. Using CoSE's layout structure as a baseline enables CoSEP to handle non-uniform node sizes, arbitrary levels of nesting, and intergraph edges that may span multiple levels of nesting. Our experiments show that CoSEP signi cantly improves the quality of the layouts for compound graphs with port constraints with respect to commonly accepted graph drawing criteria, while running in at most a few seconds, suitable for use in interactive applications for small to medium sized graphs. The CoSEP algorithm is implemented in JavaScript as a Cytoscape.js extension, and the sources along with a demo are available on the associated GitHub repository.
Open Access
Graph drawing contest report
(Springer, 2009-09) Doğrusöz, Uğur; Duncan, C. A.; Gutwenger, C.; Sander, G.
This report describes the 15th Annual Graph Drawing Contest, held in conjunction with the 2008 Graph Drawing Symposium in Heraklion, Crete, Greece. The purpose of the contest is to monitor and challenge the current state of graph-drawing technology.
Open Access
HySE: a spring embedder approach for layout of hybrid graphs
(2023-09) Islam, Hamza
In recent times, the growth of data has been exponential, making the visual analysis of relational data progressively complex. Presenting such data in a visually appealing manner can help simplify the analysis process. Hybrid graphs, comprising a central directed or hierarchical part and interconnected undirected components, offer a practical structure for representing relational data with varying levels of abstraction while managing its complexity. To comprehend the relationships in data, discover insights, and get important patterns, a well-optimized graph layout for such graphs is needed. In response, we present HySE (Hybrid Spring Embedder), a novel graph layout algorithm tailored for hybrid graphs. HySE makes use of a holistic approach based on the popular spring embedder to achieve the aesthetics and quality of an optimized force-directed layout, not only on the undirected part of the graph but also on the hierarchy while maintaining the cohesion between both directed and undirected elements of the graph. The layout algorithm assumes the rank information of directed graph elements is already calculated with one of the popular approaches. Then, it finds appropriate initial positions and uses a force-directed layout technique to integrate the undirected parts into the layout, applying spring forces to model the edges, and repulsive electric forces for the nodes. Iteratively, HySE converges to an equilibrium state with minimized energy, resulting in visually pleasing and interpretable layouts for intricate hybrid graphs. Experiments performed on graphs, generated randomly through a well-designed process, validate that HySE performs as well as the state-of-the-art algorithms in terms of quality. It also matches the speed of well-established algorithms as well in small-to-medium-sized graphs.
Open Access
A layout algorithm for undirected compound graphs
(Elsevier, 2009-03-15) Doğrusöz, Uğur; Giral, Erhan; Çetintaş, Ahmet; Civril, Ali; Demir, Emek
We present an algorithm for the layout of undirected compound graphs, relaxing restrictions of previously known algorithms in regards to topology and geometry. The algorithm is based on the traditional force-directed layout scheme with extensions to handle multi-level nesting, edges between nodes of arbitrary nesting levels, varying node sizes, and other possible application-specific constraints. Experimental results show that the execution time and quality of the produced drawings with respect to commonly accepted layout criteria are quite satisfactory. The algorithm has also been successfully implemented as part of a pathway integration and analysis toolkit named PATIKA, for drawing complicated biological pathways with compartmental constraints and arbitrary nesting relations to represent molecular complexes and various types of pathway abstractions. © 2008 Elsevier Inc. All rights reserved.
Open Access
A multi-graph approach to complexity management in interactive graph visualization
(Pergamon Press, 2006-02) Dogrusoz, U.; Genc, B.
In this paper we describe a new, multi-graph approach for development of a comprehensive set of complexity management techniques for interactive graph visualization tools. This framework facilitates efficient implementation of management of multiple associated graphs with navigation links and nesting of graphs as well as ghosting, folding and hiding of unwanted graph elements. The theoretical analyses show that the involved data structures and operations on them are quite efficient, and an implementation in a graph drawing tool has proven to be successful. © 2005 Elsevier Ltd. All rights reserved.