Overview
A short introduction to social network modelling
To produce a network, two inputs are needed: a list of the actors composing the network,
and a list of the relations (the interactions between actors). As part of a mathematical
object, actors will then be called nodes, or vertices, and relations will be denoted as edges.
Here, you can observe a very simple graph, with both lists explicited. Two attributes are
attached to the nodes : a label (his or her « name ») and his or her gender. In the edge list,
« Source » and « Target » entries refer to the nodes’ numeric Id’s.
In our example, the « gender » attribute determines the color of the nodes. The size of a
node depends on the value of its « degree » (number of connections).
Getting data from facebook:
Fan page and now groups networks from Facebook with the newly updated Social
Network Importer for NodeXL
What's New?
The new version of Social Network Importer includes a Group Network Import which
allows you to import different networks for Facebook groups.
This new version includes also a search functionality for fan pages and groups. To use
this functionality just start typing the name of the fan page/group in the textbox and it
will automatically display a list of the fan pages/groups matching the search term. Select
the fan page/group you want to analyze by clicking on it. You will then see the ID of the
selected fan page/group in the textbox.
Social Network Importer Features
The Facebook Fan Page network importer can extract connections among people and
posts linked by co-like or co-comment actions. User to user, post to post, and user to post
networks are available.
Using the ego network data importer, it is possible to extract one's own personal
Facebook friend’s network - the collection of connections among your and your friends
and your friend’s connections to one another. Visualizing this network data set can result
in a network visualization created with NodeXL that looks something like this:
How to install the Social Network Importer for NodeXL:
> Close NodeXL
> Download the zip file from http://socialnetimporter.codeplex.com/
> Unzip the file: you will find two items:
FacebookAPI.DLL
SocialNetImporter.DLL
> Copy these files to the NodeXL Plug-ins Directory specified in the "Import Options..."
(Using third-party graph data importers in NodeXL Excel Template 2014)
> Restart NodeXL: you should see the Facebook Import option in the
NodeXL>Data>Import menu.
3. Clean the database
click to enlarge
Open your .txt file in a spreadsheet application. The two lists (nodes and edges) appear to
be merged into one file, but you can quickly recognize the headings which separate both
lists.
click to enlarge
Copy the node list (generally much shorter than the edge list), and paste it in another
file. Then, delete the node list from the original file. We keep only the edges in this one.
click to enlarge
To secure the compatibility of the data with Gephi, rename the headers of the two files
as follows:
- Edges : Source,Target
- Nodes : Id,Label
Then save both files as .csv (it should appear as an available option when saving, but if
not, save it like you normally do and then rename the extension).
Now after extracting the node files, we will use Gephi to visualize them.
4. Getting started with Gephi
First of all, downloading and
easy: https://gephi.org/users/download/
installing
the
application
is
very
Our tutorial is based on the 0.8.2 Gephi beta version. If you encounter a problem due to a
later update, do not hesitate to let us know.
Now run the application on your computer, and open a « new project » in the start menu.
Import nodes
In the »Data Laboratory », click on « Import Spreadsheet » to open the import window.
Specify that the separation between your data is expressed by a comma and do not forget
to inform Gephi that the data you import is related to nodes, as demonstrated in our
example. Then press « next ».
Finally, fill in the required fields as shown here.
Import Edges
Follow the same procedure as for the nodes, but by filling it in the following manner:
specify the comma and inform Gephi that this time you import the edges.
Fill in the last fields, and uncheck « create missing nodes », because you’ve already
imported them.
5. The practice of visualization
The action now takes place on the overview panel. The software produces a overview of
the graph, spatialized randomly (and pretty illegible).
Eliminate the « noise »
The first operation consists in slightly reducing the network to its biggest component (the
biggest subset of the network in which we can find, for each couple of nodes, a way from
one node to the other). In the right column, select Filters/Library/Topology/Giant
Component and confirm by clicking « Filter ».
Nodes’ size
In the « Ranking » panel of the left column (top), select « Nodes » and the « red
diamond » (size), then select « Degree » (rolling menu) and enter the minimal and
maximal value (we propose 20-200). At that point, click on the « Spline » blue link to edit
the shape of the spline (take the 3rd template, as proposed here, in order to consider the
surface of the nodes).
Spatialization
That’s the main part! While it is possible to play (and lose yourself) with various
visualization capabilities, we propose an effective method. Start with Fruchterman
Reingold (left column, bottom), and use the same values as in our model (50000; 10; 1).
This visualization disposes nodes in a gravitational way (attraction-repulsion, in fact, as
magnets). You’re already able to distinguish communities (more densely connected parts
of the network). Let the function run until the graph is stabilized.
Then, we propose to use the Force Atlas 2 (another layout algorithm) to disperse groups
and give space around larger nodes. Be careful, the parameters you enter significantly alter
the final appearance.
Nodes’ color
As there are no categories for the nodes in the database (in our example – point 1 – the
nodes had a « gender » parameter), we propose to use once again the « degree » to assign
a color to the nodes.
Without changing the « spline », the last used applies. This is not a problem. Feel free and
creative.
6. Final details
Go to « preview » for trimming the final details. Unlike during previous stages, changing
settings in this menu is reversible, and do not affect the structure of the graph. In the
following screenshot, you will find a suggestion of settings for a good rendering :
Note that you are free to display (or not) the labels of the nodes, i.e. the names of your
facebook contacts.
Export your artwork
At the bottom of this preview column, you should find an export link. Note that exporting
in .png produces figure with a poor resolution. You may want to opt for .svg or .pdf, which
have the advantage of being modifiable by your own image/drawing software (we
recommend the open source program inkscape for manipulating .svg files).