1. Concept Map: Clustering Visualizations of Categorical Domains
David Rouff and Mark McLean
CMSC 743 Information Visualization, Spring 07
Department of Computer Science
University of Maryland

2. 1.INTRODUCTION Categorical Data Sets are hard to visualize
No inherrent order, variable size, each element and it’s associations is a dimension
Popular Node-Link quickly becomes occluded
Adjacency matrix hard to understand, elements disjoint
Concept Map visualizes categorical data with
Multiple, coordinated views
Modified hierarchical clustering and SOM clustering
Tunable clustering and display parameters

3. 3. Design Approach Mockups and prototypes guided development.
Dendrogram/Adjacency Matrix in Matlab
SOM/Node Link in Flex

4. Implementation of Dendrogram and Clustered Adjacency Matrix

5. Adaptations to Hierarchical clustering
Similarity distance calculation
FOIL

6. Interesting Features in the Dendrogram and Adjacency Matrix

7. Dendrogram and Adjacency Matrix Demo Then switch to SOM and Node Link

8. Magic… Hierarchy from Flatness and Clarity of Thought - Overview

9. Behind the Scenes Convert articles into vectors
Compress the vectors to 24-bit space
Apply vector to random SOM
Best matching unit (BMU) learns and so does its neighbors – Mexican hat
Group Clusters – low dimensional grouping
Create Node-Link Graph

10. This hierarchy can then be traversed to explore articles
Results
Proves a large corpus of articles can be reconstructed into a meaningful hierarchy
This hierarchy can then be traversed to explore articles
The node-link representation delivers a clear distance between nodes and relationship among nodes

11. Lessons learned… where to begin
Don’t bite off more than you can chew, in other words if it sounds like you are going to save the world, it might take more than 6 weeks to do it.
When up against a short deadline, don’t try to learn a new language even if they swear it decreases development time and a 6 year old can use it. (in other words Caveat Emptor)
There is always time to design no matter how small you think your program will be.
Conceptually problems are easy to solve…. Practically they aren’t

12. Analysis, user feedback, conclusion, questions…