Visualization of the similarity relationships of the yeast genes with a SOM in learning metrics. The names of the genes have been marked on the SOM units (every second hexagon) onto which they have been mapped, and the units having no genes have been marked with dots. The hexagons in between each pair of SOM units are so-called U-matrix units (see the Methods Section) whose gray shades indicate clusteredness in the region (light: cluster; dark: sparse area). The 202 genes for which the metric is the most different from the usual inner product metric have been underlined. Three sample areas analyzed briefly in the text have been circled and numbered.