Medoid Heat Maps of Axon Guidance and Time Course. Heat map of the medoids identified in (1a) axon guidance and (1b) developmental time course experiments. The medoid is a single gene from each cluster, selected by hopach as the cluster profile because its pattern of expression is the most representative of that cluster. Medoid plots provide a global overview of the clustering results. The order of clusters in these plots is uniquely determined by the hopach algorithm. Expression relative to the control is shown on a red to yellow color scale, with red indicating suppressed and yellow indicating induced expression. The number of genes represented by each profile (i.e., row) is variable from cluster to cluster. (1a) Medoids for the axon guidance data. There are distinct regions of clusters, for instance the initial 37 clusters are similar with stronger expression for the gain of function FRM and UR.mef. A distinct region follows, in which there is a significant decrease in the mutants robo, robo2, slit.robo and the transgenic UC2x. (1b) Medoids for the developmental time course. The initial clusters show only late expression with the subsequent clusters showing earlier and earlier expression. Note: the size of each cluster is not represented in this plot. For instance Cluster TC139 has 6626 genes -almost half of all microarray probes are represented by one single row.