Cell Filter Data Source

Introduction

This data source can be used when examing data with SOM. Assume that you have trained a SOM map and would like to further analyse how certain regions of the map differ from other regions. For example, this can be of interest if one identifies clusters on the map.

It is good to remember that each of the SOM map cells can be seen as a cluster centers or prototypes in original data. Thus by examining SOM map cells one can indirectly examine the original data.

To clarify the issue, lets consider the realationship between labels in data and label on SOM map. Each label is displayed on the cell which is closest to this data value. Thus data value belongs to the proximity of this SOM cell.

After some cells are selected from the SOM map, the SOMCellFilter data source output can be feeded to a standard chart. You can use, for example, a column chart.

Setup

Typical usage pattern is as follows:

<data>
   <somCellFilter>
      <cell x="5" y="6">
      <cell x="5" y="7">
      <cell x="5" y="8">
      <cell x="6" y="6">
      <cell x="6" y="7">
      <som>...</som>
   <somCellFilter>
</data>

In the example above a group of five cells are celected from the SOM map. Each cell is selected just by the coordinates. This rather crude interface can be quite handy with JSP pages and loops.

Example

For an example, see Feature Vector Visualization xml.