cnrs - upmc laboratoire d’informatique de paris 6 Gephi and network dynamics: technology and applications S´ ebastien Heymann ISCN Dynamic Network Day 2012 24 mai 2012
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cnr s - upmc laborato i r e d ’ i n format ique de par i s 6
Gephi and network dynamics:
technology and applications
Sebastien Heymann
ISCN Dynamic Network Day 201224 mai 2012
Concepts
cnr s - upmc laborato i r e d ’ i n format ique de par i s 6
Notions of dynamicsGenerally, softwares use the notion of snapshot : state of thegraph 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 2 3
WINDOW
TICKS
TIMELINE INTERVAL
TIME0 1 2 3 4 5 6
1
0 2 3
WINDOW
TICKS
TIMELINE INTERVAL
TIME0 1 2 3 4 5 6
1
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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 Swingapplications. It provides the ’plumbing’ that, before, everydeveloper had to write themselves”
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Gephi : modules
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Dynamic API
API dedicated to dynamic network states and events. Browsingdynamic networks uses the Timeline component and defines a”visible interval” (i.e. a sub-graph). This API is responsible forholding 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 slidingwindow 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 thevisualization.
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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 (intervalsopen/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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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 etal.)
J. Stehle et al. High-Resolution Measurements ofFace-to-Face Contact Patterns in a PrimarySchool. PLoS ONE 6(8): e23176
Network of contacts aggregated over the first day.Sebastien Heymann — Gephi Dynamics — 24 mai 2012
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DemoData: contact network during Hypertext 2009 over 2,5 days
Source: Sociopatterns.org
Questions?
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