Mathieu Jacomy develops digital tools for the social sciences and provides support and advice in digital methods to scholars. He investigates how digital knowledge technologies transform our relation to complex phenomena. His current research focuses on visual network analysis and exploration, issue mapping, developing tools for digital methods and reflecting on methodological aspects. Mathieu joined the Lab in September 2018. Previously, he initiated the Gephi network analysis software, notably through algorithms like ForceAtlas2, and he developed the web crawler Hyphe. His favorite research field is the world wide web and his approach is influenced by controversy mapping and actor-network theory. Since 2010, Mathieu is also a research engineer at the Sciences Po Paris médialab. He was also strongly involved in the e-Diasporas Atlas program with Dana Diminescu from 2006 to 2010.
ForceAtlas2, a Continuous Graph Layout Algorithm for Handy Network Visualization Designed for the Gephi Software
Gephi is a network visualization software used in various disciplines (social network analysis, biology, genomics…). One of its key features is the ability to display the spatialization process, aiming at transforming the network into a map, and ForceAtlas2 is its default layout algorithm. The latter is developed by the Gephi team as an all-around solution to Gephi users' typical networks (scale-free, 10 to 10,000 nodes). We present here for the first time its functioning and settings. ForceAtlas2 is a force-directed layout close to other algorithms used for network spatialization. We do not claim a theoretical advance but an attempt to integrate different techniques such as the Barnes Hut simulation, degree-dependent repulsive force, and local and global adaptive temperatures. It is designed for the Gephi user experience (it is a continuous algorithm), and we explain which constraints it implies. The algorithm benefits from much feedback and is developed in order to provide many possibilities through its settings. We lay out its complete functioning for the users who need a precise understanding of its behaviour, from the formulas to graphic illustration of the result. We propose a benchmark for our compromise between performance and quality. We also explain why we integrated its various features and discuss our design choices.
Jacomy, Mathieu, Venturini, Tommaso, Heymann, Sebastien, and Bastian, Mathieu.
In: PLoS ONE 9(6):e98679 · June 2014
Hyphe, a Curation-Oriented Approach to Web Crawling for the Social Sciences
The web is a field of investigation for social sciences, and platform-based studies have long proven their relevance. However the generic web is rarely studied in itself though it contains crucial aspects of the embodiment of social actors: personal blogs, institutional websites, hobby-specific media… We realized that some sociologists see existing web crawlers as " black boxes " unsuitable for research though they are willing to study the broad web. In this paper we present Hyphe, a crawler developed with and for social scientists , with an innovative " curation-oriented " approach. We expose the problems of using web-mining techniques in social science research and how to overcome those by specific features such as step-by-step corpus building and a memory structure allowing researchers to redefine dynamically the granularity of their " web entities " .
Jacomy, Mathieu, Girard, Paul, Ooghe-Tabanou, Benjamin and Venturini, Tommaso.