The document discusses exploratory network analysis using the open-source network visualization platform Gephi. It describes how Gephi allows users to interact with network data at different levels (micro, macro, dimensions) and time scales to extract meaningful patterns and structural properties. "Zoom", "Crossing" and "Timeline" cursors are introduced as ways to analyze quantitative, qualitative and temporal network data. Examples of using Gephi to analyze collaborations, themes, actors and territories in a network are provided. Key aspects of Gephi like extensibility and the nonprofit community behind it are summarized.

1. Sébastien Heymann <seb@gephi.org>

3. Exploratory Network Analysis
2 interact in real time
1 see the network
Gephi prototype (2008)
1st graph viz tool: Pajek (1996) group, filter, compute metrics...
Vladimir Batagelj, Andrej Mrvar
3 build a visual language
size by rank, color by partition,
label, curved edges, thickness...

4. Looking for Orderness in Data
Make varying 3 cursors simultaneously to extract
meaningful patterns (statistical and structural properties)
MICRO level MACRO level
at different levels
1 dimension N dimensions
on multiple dimensions
T+0 T+N
at time scale

5. “Zoom” cursor on Quantitative Data
MICRO level MACRO level
Global
- connectivity
- density
- centralization
Local
- communities
- bridges between communities
- local centers vs periphery
Individual
- centrality
- distances
- neighborhood
- location
- local authority vs hub

6. “Crossing” cursor on Qualitative Data
1 dimension N dimensions
Social
- who with whom
- communities
- brokerage
- influence and power
- homophily
Semantic
- topics
- thematic clusters
Geographic
- spatial phenomena

7. “Timeline” cursor on Temporal Data
T+0 T+N
Evolution of social ties
Evolution of communities
Evolution of topics

8. Mapping an Innovation Center
Collaborations on projects at Images et Réseaux
Themes and content
Actors
Territory
Franck Ghitalla & Ecole de Design de Nantes

9. Gephi in a Nutshell
« Like Photoshop™ for graphs. »
Helps data analysts to reveal patterns and trends,
highlight outliers and tells story with their data.
• Network visualization platform
• Open source, supported by a community
• Built for performance and usability
• Extensible by plug-ins
• Windows, MacOS X, Linux

10. Gephi Community
Nonprofit organization
Communities Contributors
Mathieu Bastian, Mathieu Jacomy,
Eduardo Ramos Ibañez, Sébastien
Heymann, Guillaume Ceccarelli,
André Panisson, Antonio Patriarca,
Cezary Bartosiak, Martin Škurla,
Patrick McSweeney, Yi Du, Hélder
Suzuki, Daniel Bernardes, Ernesto
Aneiro, Keheliya Gallaba, Luiz
Ribeiro, Urban Škudnik, Vojtech
Bardiovsky, Yudi Xue

11. Community Mission
Provide a “sustainable” software
Maintain the technical ecosystem
Build a business ecosystem
Face cutting-edge technological challenges with
a long-term vision
Distribute the software in Open Source

12. Community Values
Open innovation: ideas and features come from
the entire community.
Decisions are taken with transparency.
We consider this technology as a public good,
and will keep it in open source.

13. Diversity of Usages
business leisure :-)
communication academic art

14. Diversity of Network Encoding
V = { a, b, c, d, e } <graph>
E = { (a,b), (a,d), (b,c), (e,a), (c,e) } <nodes>
<node id=”a” />
<node id=”b” />
Textual <node id=”c” />
<node id=”d” />
<node id=”e” />
</nodes>
<edges>
<edge source=”a” target=”b” />
<edge source=”a” target=”d” />
a b c d e <edge source=”b” target=”c” />
a - 1 - 1 - <edge source=”e” target=”a” />
<edge source=”c” target=”e” />
b - - 1 - -
</edges>
c - - - - 1 </graph>
d - - - - -
e 1 - - - - XML
Graphical
Tabular
and many others...

15. Software I/O
}
MySQL
PostgreSL
SQL Server
databases user input
Neo4j
CSV CSV
Pajek NET Pajek NET file
Guess GDF Guess GDF
>
GEXF GEXF
GraphML GraphML
file Graphviz DOT Excel Spreadsheet
UCInet DL SVG
NetdrawVNA PDF
Tulip TLP PNG
Excel Spreadsheet
graph streaming