Introduction to SOM Toolbox

The SOM Toolbox is a software library for Matlab 5 implementing the Self-Organizing Map (SOM) algorithm.

Thus far, the most useful implementation of the SOM and related tools known to the present authors has, without any question, been the SOM_PAK. It is a public domain software package developed in the Neural Networks Research Centre of the Helsinki University of Technology, written in C language for UNIX and PC environments.

Matlab:

However, the Mathworks Inc.'s Matlab has been steadily gaining popularity as the "language of scientific computing". For quite a while, the Matlab Neural Networks Toolbox has included a couple of functions that are related to the SOM. These are, however, primarily for demonstrations of the self-organization process and, as such, not sufficient for practical data analysis applications. As far as we know the SOM Toolbox is the first such software for Matlab.

So there seemed to be a need also for a Matlab implementation of the algorithms found in SOM_PAK. Moreover, we felt that Matlab might be better-suited for fast prototyping and customizing than the C language used in SOM_PAK, as Matlab employs a high-level programming language with strong support for graphics and visualization. It is because of these two reasons that we considered it worthwhile to develop the SOM Toolbox.

Toolbox and SOM_PAK:

We have tried to take full advantage of the strengths of the Matlab, and therefore the SOM Toolbox is not just a SOM_PAK rewritten for Matlab but more like a new set of programs. On the other hand, it must be emphasized that the SOM Toolbox is intended to complement the SOM_PAK, not to replace it. Both program packages have their relative strengths and weaknesses, some of which are roughly characterized below:

Most features found in the SOM_PAK are in some form available also in the SOM Toolbox. The SOM_PAK files can also be accessed with the Toolbox, so it is possible to first train the map with the SOM_PAK and then use the Toolbox for map visualization.

Highlights:

Highlights of the SOM Toolbox include the following:

Related links:


somtlbx@mail.cis.hut.fi
Last modified: Fri Nov 7 19:56:00 EET 1997