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A Circos-Inspired Interactive Web Client Based Tool for Improving the Clarity of Tabular Data Visualization

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A Circos-Inspired Interactive Web Client Based Tool for Improving the Clarity of Tabular Data Visualization TabularVis – A Circos-inspired Interactive Web Client based Tool for Improving the Clarity of Tabular Data Visualization Gyorgy¨ Papp and Roland Kunkli Department of Computer Graphics and Image Processing, Faculty of Informatics, University of Debrecen, Debrecen, Hungary Keywords: Data Visualization, Circular Layout, Sorting, Table, Diagram, Search Algorithm. Abstract: Table visualization is one of the earliest problems in the field of data visualization, and there are many appli- cations which provide different solutions to this task. One of the most popular ones is Circos, a well-known genome visualization software package based on the so-called circular layout technique. In this work, we present an interactive web-based visualization tool inspired by Circos’ table viewer web application, in which we provide new extensions and techniques beyond its existing main ideas, for improving the clarity of the generated visualization. One of them is making the links easier to follow by giving an automatic solution to reduce the number of intersections between the links. We also present different tools which could be particu- larly useful in such situations, in which the table’s data induce extreme scatter, i.e., the difference between the data is significantly large or small. Our proposed visualization accepts tables with non-negative numbers, and the amount of efficiently displayable data depends on the number of zeros in the table. In the paper, besides describing our contributions in detail, we also compare the outputs of our method and Circos table viewer to confirm the legitimacy of our application and the implemented techniques it contains. 1 INTRODUCTION including the highly cited and popular Circos soft- ware package (Krzywinski et al., 2009). In this paper, Nowadays, it is difficult to find a scientific or indus- we present an improved approach of how Circos vi- trial field, in which the relationships between data do sualizes connections based on tables, by giving new not play an important role. Almost everything affects tools for displaying the value, the direction, and the something else, and it is crucial to notice these de- pattern of the connections. Sometimes it is confus- pendencies and understand the relationships that they ing to follow the links in a diagram, so we introduce describe. The connections are often represented by a sorting method as well, to make the diagrams more values, and each one can indicate the related connec- transparent by reducing the number of intersections tion’s type or property. between the connections. Multiple search and opti- Tables have a long history in database manage- mization algorithms were implemented for this task, ment and computer science, and they suit well to store and we compare them with each other to find the one information about relationships. In this paper, we deal with the best performance. with connections which are represented by numbers. In this work, first, we discuss the related works, However, organizing these connections into a table then in Section 3.2, we introduce our visualization does not make them easily readable or understandable method in detail. Also, we briefly present Circos to by itself, because when a table is formed by many make the comparison of the two visualization solu- rows and columns, it becomes harder to work with tions easier. After this, we propose our solution for it. There are a lot of various reasons and purposes reducing the intersections of the connections. At the why the users want to visualize tables, and what they end of the paper, we introduce the features and the want to see in the resulting image. By using tabu- performance of our self-developed application, which lar visualization, our goal is to display relationship was implemented to present our results. information. There are a lot of different techniques to achieve this goal, but the circular layout is one of the most prominent ones. It is used in the field of graph drawing and many visualization applications, 120 Papp, G. and Kunkli, R. TabularVis – A Circos-inspired Interactive Web Client based Tool for Improving the Clarity of Tabular Data Visualization. DOI: 10.5220/0006620701200131 In Proceedings of the 13th International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications (VISIGRAPP 2018) - Volume 3: IVAPP, pages 120-131 ISBN: 978-989-758-289-9 Copyright © 2018 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved TabularVis – A Circos-inspired Interactive Web Client based Tool for Improving the Clarity of Tabular Data Visualization 2 RELATED WORK data better and faster. Unfortunately, the possibility of customizing the diagram in the way of removing or changing its elements is missing in these two men- Circular layout is often used to visualize connections, tioned applications. In turn, this functionality could especially for genomic data or graphs. However, its help to make the diagram more personalized. Addi- advantages, which come from its simplicity and sym- tionally, these software still operate with one or more metry, make it perfect to visualize other general data configuration files, which is still not the most user- as well. The rotation invariant property, the ability to friendly solution. However, both applications have reduce the number of eye movements, and weakening inspired us to extend the possibilities of visualizing the reading order implications are just three of these the connections’ values in a diagram. advantages, which are discussed in the work of Chuah and Eick (Chuah and Eick, 1998). Beside genomic data, there is a demand for soft- ware solutions and tools for visualizing relationships In these referenced works we can see examples of and connections based on more general data. The genome (Katapadi et al., 2012; Burkart-Waco et al., R package called circlize (Gu et al., 2014) can cre- 2012; Schmutz et al., 2014; Tine et al., 2014), net- ate diagrams based on non-genomic data. The main work (Lin et al., 2014; Dang et al., 2015; Irimia and purpose of circlize is still the genomic analysis, but Horn, 2013; Irimia and Van Horn, 2014), and general thanks to its low-level graphic functions, the user can (Blasco-Soplon´ et al., 2015; Pan et al., 2013; Fuji- use it for displaying other kinds of data. Circos can wara, 2015; Nicholas et al., 2014) data visualization visualize general data as well, but they have to be by researchers from different disciplines. There are a given in one of the required formats. The InfoVis li- lot of studies which show good use cases for how the brary (Li, 2012) has a visualization tool called Smith- circular layout can easily visualize the connections; Graph which uses bars on the circle’s circumference. here we would like to mention some of them. Circos A similar visualization method is Jen Lowe’s solution is an open-source and free application licensed under (Bayer, 2011), with which she has won the WikiViz GPL. Also, it is widely used in the field of genome 2011 challenge. research, because of its success in displaying varia- tion in genome structure and positional relationship There is a trend to bring the visualization right between genomic intervals. Besides, it can show dif- into the browser and make it as interactive as much ferent plot types inside the tracks of the diagram, to as possible. Probably the most used tools for this provide more information about genomes. However, kind of purpose are the D3.js (Bostock et al., 2011) despite the fact that Circos is a powerful visualiza- and the WebGL libraries. There are many examples tion tool, unfortunately, it is not user-friendly at all. It in the Chrome Experiments website (creative coding is a command line application written in Perl, and it community, 2009), and WebGL also has been used in uses configuration files to create the diagrams. More- different scientific visualization projects (Mwalongo over, learning how to use the software can be hard and et al., 2015; Andrews and Wright, 2014; Bornelov¨ time consuming for researchers with basic IT skills. et al., 2014; Cui et al., 2016). Circos also has an on- There are numerous applications, for example, ggbio line application for tabular data visualization, but it (Yin et al., 2012), Rcircos (Zhang et al., 2013), or has less much less functionality than the desktop ver- OmicCircos (Hu et al., 2014), which aim to provide sion of the software. a more user-friendly and improved circular genome As we have pointed out above, the circular layout visualization. These mentioned applications are pack- has proven its ability to visualize both genomic and ages which have been developed for the R statistical general data. Also, few examples have been shown software environment. By using them, it is ensured how the lack of interactive functionality can nega- that the users can take the advantages of R while they tively affect the usability of an application. Besides, are creating visualizations. However, only static im- we have seen that there is a need for an easily acces- ages can be generated with all the applications that sible and user-friendly web-based application. we mentioned so far, and this makes it significantly It is easy to imagine that a diagram can quickly harder to customize the diagrams after they were cre- become crowded if there are too many connections ated. The possibly used third party software or any in it, and this may prevent the user from understand- framework assumes the knowledge of them, and they ing the data. Decreasing the number of intersections can make the installation of the application more com- between graph edges during a circular graph drawing plex and time-consuming. The circular layout com- is a well-known problem in the field of graph theory. bined with interactive data visualization techniques In the work of Baur et al.
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