Gephi Bits 2: A Further Look at Comments on Social Objects in a Closed Community

In the previous post in this set (Gephi Bits 1: Comments on Social Objects in a Closed Community), I started having a play with comment and favourites data from a series of peer review activities in the OU course Design thinking: creativity for the 21st century.

In particular, I loaded simple pairwise CSV data directly into Gephi, relating comment id and favourite ids to photo ids. The resulting images provided a view over the photos that showed which photos were heavily commented and/or favourited. Towards the end of the post, I suggested it might be interesting to be able to distinguish between the comment and favorite nodes by colouring them somehow. So let’s start by seeing how we might achieve that…

The easiest way I can think of is to preload Gephi with a definition of each node and the assignment of a type label to each node – photo, comment or favourite. We can then partition – and colour – each node based on the type label.

To define the nodes and type labels, we can use a file defined using the GUESS .gdf format. In particular, we define the nodes as follows:

nodedef> name VARCHAR, ltype VARCHAR
p189, photo
p191, photo

c1428, comment
c1429, comment

f1005, fave
f1006, fave

Load this file into Gephi, and then append the contents of the comment-photo and favourite-photo CSV files to the graph. We can then colour the nodes (sized according to, err, something!) according to partition:

Coloured partitions in Gephi

If we filter the network for a particular photo using an ego filter, we can get a colour coded view of the comment and favourite IDs associated with that image:

Coloured nodes and labels in Gephi

What we’ve achieved so far is a way of exploring how heavily commented or favourited a photo is, as well as picking up a tip or two about labeling and colouring nodes. But what about if we wanted a person level analysis, where we could visually identify the individuals who had posted the most images, or whose images were most heavily commented upon and favourited?

To start with, let’s capture some information about each of the nodes. In the following example, we have an identifer (for a photo, favourite or comment), followed by a user id (the person who made the comment or favourite, or who uploaded the photo), and a label (photo, comment or fave). (The ltype field also captures a sense of this.)

nodedef> name VARCHAR, username VARCHAR, ltype VARCHAR
p189,jd342,photo
p191,jd342,photo
p192,pn43,photo
..
c1189,pd73,comment
c1190,srs22,comment
..
f46,ww66,fave
f47,ee79,fave

Rather than describe edges based on connecting comment or favourite ID to photo ID, we can easily generate links of the form userID, photoID, where userID is the ID of the user making a comment or favouriting an image. However, it is possible to annotate the edges to describe whether or not the link relates to a comment or favouriting action. So for example:

edgedef> otherUser VARCHAR, photo VARCHAR, etype VARCHAR
pd73,p189,comment
srs22,p226,comment

ww66,p176,fave

Alternatively, we might just use the simpler format:
edgedef> otherUser VARCHAR, photo VARCHAR
pd73,p189
srs22,p226

ww66,p176

In this simpler case, we can just load in the node definition gdf file, and follow it by adding the actual graph edge data from CSV files, which is what I’ve done for what follows.

Firstly, here’s the partition colour palette:

Gephi - partition colours

The null entities relate to nodes that didn’t get an explicit node specification (i.e. the person nodes).

To provide a bit of flexibility over the graph, I loaded the the favourites and comment edges in as directed edges from “Other user” to photo ID, where “Other user” is the user ID of the person making the comment or favourite.

If we size the graph by out-degree, we can look at which users are actively engaged in commenting on photos:

Gephi - who's commenting/favouriting

The size of the arrow depicts whether or not they are multiple edges going from one person to a photo, so we can see, for example, where someone has made multiple comments on the same photo.

If we size by in-degree, we can see which photos are popular:

Gephi - what photos are popular

If we run an ego filter over over a photo id, we can see who commented on it.

However, what we would really like to be able to do is look at the connections between people via a photo (for example, to see who has favourited who’s photos). If we add in another edge data file that links from a photo ID to a person ID (the person who uploaded the photo), we can start to explore these relationships.

NB the colour palette changes in what follows…

Having captured user to photo relationships based on commenting, favouriting or uploading behaviour, we can now do things like the following. Here for example is a use of a simple filter to see which of a user’s photo’s are popular:

Gephi - simple filter

If we run a simple ego filter, we can see the photos that a user has uploaded or commented on/favourited:

Gephi - ego filter

If we increase the depth to 2, we can see who else a particular user is connected to by virtue of a shared interest in the same photographs (I’m not sure what edge size relates to here…?):

Ego depth 2 in gephi - who connects to whom

Here, user ba49 is outsize because they uploaded a lot of the images that are shown. (The above graph shows linkage between ba49 and other users who either commented on/favourited one of ba49’s images, or who commented/favourited photo that ba49 also commented on/favourited.)

Doh – it appears I’ve crashed Gephi, so as it’s late, I’m going to stop for now! In the next post, I’ll show how we can further elaborate the nodes using extended user identifiers that designate the role a person is acting in (eg as a commenter, favouriter or photo uploader) to see what sorts of view this lets us take over the network.

Author: Tony Hirst

I'm a Senior Lecturer at The Open University, with an interest in #opendata policy and practice, as well as general web tinkering...

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