Introduction to Network Analysis in Gephi

Intro to
Network Analysis in Gephi
victor.Blaer@gmail.com

Disklaimer
The right mindset
Network visualization is messy. You get into technical difficulties and have to search the internet and peoples minds for
solutions. The data itself is often inconsistent and you need to find ways to still get insights from it. The whole process is
full of trial and error with many dead ends. There is no undo for most actions in network visualization. If you like a specific
view on the data, better export it, because with the press of a button it may look totally different and even if you start with
the same file and do the same things, the result will probably look different. It is possible to re-create certain views, but it
takes a lot of time.
Get ready to get your hands dirty and spend hours without getting anywhere and keep going or starting fresh the next day.
Over time it gets better. You will learn other peoples tricks and develop your own to get faster to useful results. You will
experience the bliss of data that finally makes sense and the satisfaction when you share a beautiful visualization with
others.
Keep going, share your process, save often and have fun.

Goals
Super Duper Quick intro to Gephi
Basic Network Lingo to sound like the kool kids
Nodes, Edges and the Restaurant at the End of the Universe
Visualizing Co-workers (no, not that way.)
IF (Time_Left) > 5 mins THEN “sigma.js” ELSE END.

What is Gephi?
Created in 2008 by 4 French computing engineers
Free java based open source software to analyse and visualize
networks

Get the audience involved
Let’s put the FUN into FUNdamentals
Interactive exercise

Definitions-ish
Ω Nodes – represent the entity you’re analysing
Ω Edges – represent the connections between them
Ω Degree – the number of edges/lines coming and
going from the circle things
Ω Modularity – the different type of communities within
your network (i.e. workmates, sports teams,
etc.

Understanding the Interface of Gephi
Ω Three Different Views: Overview, Data Laboratory and
Preview
Ω The Overview is used to work interactively with the graph.
Ω The Data Laboratory gives you the raw data as a table.
Ω The Preview is used to generate beautiful looking versions of
the graph. Each view accesses the same graph. If you change
something in the Overview it’s changed in the Data Laboratory
and the Preview as well.

Overview
This is where you spend most of
the time interactively exploring a
graph. You can define how nodes
and edges look, use different
algorithms to calculate the layout
of the graph, use filters to work
only with certain parts of the graph
and calculate various statistics.

Layout The layout area gives you access to
various algorithms, you can use to
calculate the layout of your graph. Each
algorithm has it advantages and
disadvantages. For social network
graphs ForceAtlas 2 or OpenOrd is a
good starting point. Some algorithm finish
themselves, some need to be stopped
once you like the result. Some algorithms
can be run after others and only do
minimal adjustments (expansion,
contraction, noverlap, label adjust) others
will completely change how the graph
looks like. You can click on each setting
of each algorithm to get additional
information of what it does.
Helps with spreading nodes
out (I use 10 )

Statistics & Filters
While the statistics options
aren’t self explaining, they all
work the same. You click on
Run and get a results page
displayed. As long as you don’t
want to write a paper on a
graph, you probably only need
Modularity, which identifies
sub-communities

Graph
In the center of the Overview view is the
Graph. You can move around by holding the
right mouse button, zoom with your scroll
wheel and select/drag/color/??? nodes by
clicking left on them.
Each of the settings on the side and bottom
has a mouse over tooltip. Be careful with the
settings at the bottom left. The first one, the
magnifying glass is useful, when you get lost,
because it centers the view on your graph.
The three settings below reset colors and
sizes. Irreversible. The buttons and the
bottom help you to make the graph more
readable or exploreable at all, if it’s to big.
Turning of the display of edges helps a lot in
such cases.

Data Laboratory
The Data Laboratory gives you the
raw data. You can switch between
nodes and edges. Through the
configuration you can set if you
want to see everything or only the
things that are visible in the
Overview. For example if you
activated a certain filter, you
probably want to only see the things
that fit to the filter. You can export
the data or import it and other
things. Sometimes you don’t need
to do anything here, especially with
a nicely prepared data set.

Preview
Once you are happy with your graph, you can use the Preview to render it. There are different presets
and many settings to render it as you want it. At the bottom left you have the option to export it as
SVG, PDF or PNG. With the Preview ratio, you can set to only render a percentage of the whole
graph. This helps a lot if you need to find the right settings for a big graph which takes some minutes
to hours to be render completely. In the Preview you move around by holding the left mouse button
while moving. Think of it as grabbing the whole image and moving it. You can also zoom in and out.
But you can choose nodes or do other things you can do in the Overview.

OK, now we got the lingo,
let’s get some data!

1-Nodes/Actors
2-Edges (how
they’re connected)

Step 1- After install, click new project

Step 2: In this example we are going to import that data from CSV files and we are going to
use them for ease of use. Once you click New Project you will get the following Screen,
then click Data Laboratory for importing data.

Step 3: Once you Open the Data Laboratory pane now you click Import Spreadsheet. First
import the as table: “Nodes table” with browsing the nodes.csv. Then click next and Finish.
Nota Bene – Node file
Make sure that the CSV file containing
nodes needs to include a column named
“ID” containing unique node indentifiers.

Which will result in the following once you
click the finish button.

Step 4: Now you again click Import Spreadsheet. First import the as table: “Edges table”
with browsing the Edges.csv. Then click next and Finish.
Nota Bene – Edges file
The edge list CSV should include columns
titles “Source” & “Target”
containing the node IDs of the start and
end node for each edge, as well as any
other attributes you would like to include.

The results will be available once you click on
the Edges in the Data Table as given below:

Steps 5: Now when you click the overview
button right below the toolbar you can see the
following network diagram created.

Step 6: We can use the Layouts to make it
look little better using the Force Atlas 2 and
Label Adjust to look clean and better.

Introduction to Network Analysis in Gephi

1 node with 5 degrees, 2 with 4 and 3
with 3 degrees

To Summarize – Went from (Node) &
(Edge) to

Male
Fem
ale
Ambi
guou
s
Colouring
nodes by
gender

Playing with different Layout algorithms is
a good idea as well

Twitter Data set from interwebs (my viz)

Introduction to Network Analysis in Gephi

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