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Gephi Workshop 1. David Crowley Maciej Dabrowski. Open Gephi On the lab machines it might have to “install” or “download” it but should only take 2-3 mins We are going to play with the “Les- Miserables.gexf ” sample file to start - PowerPoint PPT Presentation
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Copyright 2011 Digital Enterprise Research Institute. All rights reserved.
Digital Enterprise Research Institute www.deri.ie
Enabling Networked Knowledge
Gephi Workshop 1
David CrowleyMaciej Dabrowski
Digital Enterprise Research Institute www.deri.ie
Enabling Networked Knowledge
Open Gephi On the lab machines it might have to “install” or
“download” it but should only take 2-3 mins
We are going to play with the “Les-Miserables.gexf” sample file to start
Save a copy so you can always start again with the original file
Digital Enterprise Research Institute www.deri.ie
Enabling Networked Knowledge
Les Miserables Network
Co-appearance weighted network of characters in the novel “Les Miserables” from Victor Hugo.
Nodes are placed randomly so it may look different for you
Digital Enterprise Research Institute www.deri.ie
Enabling Networked Knowledge
Layouts
Layout algorithms sets the graph shape, it is the most “essential action” (for visualising)
Graphs are usually layouted with “Force-based” algorithms. Their principle is easy, linked nodes attract each other and non-linked nodes are pushed apart
Layout Panel Shows layout choice And Layout Properties
Digital Enterprise Research Institute www.deri.ie
Enabling Networked Knowledge
Force Atlas 2
Run the layout for a few seconds and press stop
You should end up with a graph like this (not exactly the same or it could even be quite different)
Digital Enterprise Research Institute www.deri.ie
Enabling Networked Knowledge
Layout Properties
The purpose of Layout Properties is to let you control the algorithm in order to make a aesthetically pleasing representation
Change Scaling (repulsion) to a high number and see what happens and then make it small
Each time we need to run and stop the layout before any visible change happens.
Digital Enterprise Research Institute www.deri.ie
Enabling Networked Knowledge
Layout with Scaling @ 50
Digital Enterprise Research Institute www.deri.ie
Enabling Networked Knowledge
Ranking
Choose Ranking on the Right Hand Side panel above the layout panel
Nodes should be selected
In the drop down menu you should have three options Degree Indegree Outdegree
Digital Enterprise Research Institute www.deri.ie
Enabling Networked Knowledge
Ranking
Choose Degree Click Apply
Now your graph should be coloured in
You can change the colour settings by clicking on the colour bar
Digital Enterprise Research Institute www.deri.ie
Enabling Networked Knowledge
Result List
Click on Result List as highlighted by the red arrow
Click Apply
Now you should see the nodes listed by Rank
Digital Enterprise Research Institute www.deri.ie
Enabling Networked Knowledge
Metrics
We will calculate the average path length for the network.
It computes the path length for all possibles pairs of nodes and give information about how nodes are close from each other
Digital Enterprise Research Institute www.deri.ie
Enabling Networked Knowledge
Choose Directed – Click OK
Digital Enterprise Research Institute www.deri.ie
Enabling Networked Knowledge
Ranking
In the Ranking Panel now in Nodes, we have more metrics
Every (or almost every time) you run a metric you add a new way to rank the graph
Digital Enterprise Research Institute www.deri.ie
Enabling Networked Knowledge
Ranking (size) with overlap turned off
Digital Enterprise Research Institute www.deri.ie
Enabling Networked Knowledge
Community Detection (Modularity)
Community Detection – used a lot!
Can we predict collapse of online communities?
Concept of hubs – key points in the network
Crime networks – old studies on white collar crime
Digital Enterprise Research Institute www.deri.ie
Enabling Networked Knowledge
Modularity
Run modularity
Now you can rank nodes by modularity
This should identify “communities”
Digital Enterprise Research Institute www.deri.ie
Enabling Networked Knowledge
Partition
If you click on Partition (next to Ranking)
Press Refresh
You can partition by Modularity Class