Laboratory of Computer and Information Science / Neural Networks Research Centre CIS Lab Helsinki University of Technology

Getting started with SOM Toolbox

System requirements

System requirements are listed here.

Installing SOM Toolbox

The Toolbox can be downloaded for free from

Once you have downloaded the relevant files, move them to an approriate directory and decompress them using, e.g., unzip, pkunzip or winzip.

After this, install the Toolbox (, the date may be different) like you would install any other toolbox. If you don't know how to do that, just make sure that when you want to utilize the SOM Toolbox you are either in the Toolbox directory, or that directory is in your matlabpath (see commands path, addpath and pathtool).

The documentation (, the date may be different) includes HTML-files and some papers in PostScript, PDF or MS-Word formats. The HTML-files should go to the HelpDesk, but I have no idea currently how to add things to HelpDesk. Just put them somewhere where you can easily find them.

Creating your first SOM

There are only a few very simple commands which are needed to make and visualize a SOM of your data.

  1. First, of course, you have to get the data from somewhere. If it is in an ASCII file, you can use som_read_data function, e.g.:

    D = som_read_data('');

    or you can contruct a data set:

    D = rand(1000,2);

    Note that the columns of the data matrix should be variables, and the rows are samples.

  2. Then, construct the map with som_make function:

    sM = som_make(D);

  3. Finally, visualize the map with som_show function:


What next?

The SOM Toolbox contains a whole lot of functions other than som_read_data, som_make and som_show. For a quick list, see Contents.m in the SOM Toolbox directory. Also, the demos are there to show you around and give you a grasp of what can be done and how.

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