Landmark Map: An Extension of the Self-Organizing Map for a User-Intended Nonlinear Projection
This work addresses the problem of enhancing data visualization and interaction for users in fields like data mining and human-computer interaction, though it is incremental as it extends existing SOM methods.
The study tackled the limitation of self-organizing maps (SOMs) in incorporating user-defined relationships between data and node locations by proposing the landmark map (LAMA), which uses landmarks to achieve user-intended nonlinear projections, as demonstrated through analyses on the Zoo dataset and an artificial formant dataset showing new data views and successful associations with cursor movement.
The self-organizing map (SOM) is an unsupervised artificial neural network that is widely used in, e.g., data mining and visualization. Supervised and semi-supervised learning methods have been proposed for the SOM. However, their teacher labels do not describe the relationship between the data and the location of nodes. This study proposes a landmark map (LAMA), which is an extension of the SOM that utilizes several landmarks, e.g., pairs of nodes and data points. LAMA is designed to obtain a user-intended nonlinear projection to achieve, e.g., the landmark-oriented data visualization. To reveal the learning properties of LAMA, the Zoo dataset from the UCI Machine Learning Repository and an artificial formant dataset were analyzed. The analysis results of the Zoo dataset indicated that LAMA could provide a new data view such as the landmark-centered data visualization. Furthermore, the artificial formant data analysis revealed that LAMA successfully provided the intended nonlinear projection associating articular movement with vertical and horizontal movement of a computer cursor. Potential applications of LAMA include data mining, recommendation systems, and human-computer interaction.