Talk given at Dynamic Network Day 2012, Université du Havre, France

1. cnrs - upmc laboratoire d’informatique de paris 6
Gephi and network dynamics:
technology and applications
S´bastien Heymann
e
ISCN Dynamic Network Day 2012
24 mai 2012

2. Concepts

3. cnrs - upmc laboratoire d’informatique de paris 6
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¿