Graphics Reference
In-Depth Information
Figure
.
.
Projection of the clusters into the plane spanned by SPD and CDU/CSU, and the
corresponding Voronoi partition
each point to the closest centroid. For visualization, we can use a two-dimensional
slice through space, with the simplest case being planes spanned by two of the origi-
nal variables. Figure
.
shows the clusters projected into the plane spanned by SPD
andCDU/CSU,andthecorrespondingVoronoi partition. heplots aresimilar tothe
PCA plot in Fig.
.
; the main differences are that the eastern states are less strongly
separated from the west, and that the plot is approximately mirrored at the main
diagonal: cluster five is now in the upper let corner instead of the lower right (the
same idea applies for the remaining three western clusters). Note that the Voronoi
partition is only valid for points in the SPD-CDU/CSU plane, so the original data
points may belong to a different region in this plot compared to their original cluster
membership.
Neighborhood Graphs
11.3.3
Leisch(
)introducesaneighborhoodgraphofthecentroids,whereeachcentroid
formsanode,andtwonodesareconnectedbyanedgeifthereisatleastonedatapoint
