This document discusses Gephi, a modular software for exploring and manipulating dynamic network graphs. It describes Gephi's architecture, including its use of the Netbeans platform and modular design. The document outlines Gephi's dynamic network visualization and analysis capabilities, such as its dynamic API, timeline component, and handling of temporal network events. It also covers how dynamic network data can be imported into Gephi using formats like GEXF and via a streaming API, and provides examples of applications like social network and contact network analysis.

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Gephi and network dynamics:
technology and applications
S´bastien Heymann
e
ISCN Dynamic Network Day 2012
24 mai 2012

2. Concepts

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Notions of dynamics
Generally, softwares use the notion of snapshot : state of the
graph at each moment.
Example: Stanford SoNIA (Skye Bender-deMoll and McFarland, Daniel A. (2006) ”The Art and
Science of Dynamic Network Visualization.” Journal of Social Structure. Volume 7, Number 2)
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Notions of dynamics in Gephi
• no snapshot.
• but ”lifetime” of nodes, edges and attributes.
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Temporal Intervals
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Sliding window
0 1 2 3 TICKS
WINDOW
0 1 2 3 4 5 6 TIME
TIMELINE INTERVAL
0 1 2 3 TICKS
WINDOW
0 1 2 3 4 5 6 TIME
TIMELINE INTERVAL
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7. Technology

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Gephi : modular architecture
Stand-alone application or Java library (Gephi Toolkit)
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Netbeans Platform
”The NetBeans Platform is a generic framework for Swing
applications. It provides the ’plumbing’ that, before, every
developer had to write themselves”
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Gephi : modules
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Dynamic API
API dedicated to dynamic network states and events. Browsing
dynamic networks uses the Timeline component and defines a
”visible interval” (i.e. a sub-graph). This API is responsible for
holding and modifying that value.
• Retrieve/Set the current visible interval
• Get the current time format (date, double, datetime)
• Create DynamicGraph, a utility class to apply a sliding
window on a dynamic graph.
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Dynamic statistics
• select the size of the sliding window
• select the progression step
• # nodes, # edges, degree, clustering coefficient
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Timeline
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Timeline animation
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Sparklines and intervals of existence
for the dynamic attributes
Existence, color and size of nodes updated in real-time in the
visualization.
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Data import
• Excel spreadsheet with columns ”start” and ”end”.
• Database with columns ”start” and ”end”.
• Graph file in GEXF.
• Stream of network events through the Graph Streaming API.
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GEXF
• GEXF is an format XML.
• Standard promoted by the Gephi Consortium.
• Specifications started in 2007, stable version Dec. 2010
• Topology, attributes, hierarchy, phylogeny, dynamics (intervals
open/closed, time periods)
• Extensible via namespaces
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Stream of events
HTTP server provided by the GraphStreaming plugin. Events:
• an: Add node
• cn: Change node
• dn: Delete node
• ae: Add edge
• ce: Change edge
• de: Delete edge
Exemple: add node A (JSON format)
{”an”:{”A”:{”label”:”Node A”,”size”:2}}}
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19. Applications

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Applications
• Temporal evolution of the blogosphere.
• Contact network (SocioPatterns.org/datasets).
• Document mining (Quid, Inc.).
• Visualisation of Twitter (RT or #, e.g. the Royal Wedding).
• Real-time crawl.
• Others, e.g. source code evolution.
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Face-to-face contacts
SocioPatterns.org (Alain Barrat, Ciro Cattuto et
al.)
J. Stehl´ et al. High-Resolution Measurements of
e
Face-to-Face Contact Patterns in a Primary
School. PLoS ONE 6(8): e23176
Network of contacts aggregated over the first day.
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22. Demo
Data: contact network during Hypertext 2009 over 2,5 days
Source: Sociopatterns.org

23. Questions?

24. Thank you !
¡seb@gephi.org¿