Visualization of Asymmetric Clustering Result with Digraph and Dendrogram

Asymmetric cluster analysis is one of the most useful methods together with asymmetric multidimensional scaling (MDS) to analyze asymmetric (dis)similarity data. In both methods, visualization of the result of the analysis plays an important role in the analysis. Some methods for visualizing the result of the asymmetric clustering and MDS have been proposed (Saito and Yadohisa, Data Analysis of Asymmetric Structures, Marcel Dekker, New York, 2005). In this paper, we propose a new visualization method for the result of asymmetric agglomerative hierarchical clustering with a digraph and a dendrogram. The visualization can represent asymmetric (dis)similarities between pairs of any clusters, in addition to the information of a traditional dendrogram, which is illustrated by analyzing the symmetric part of asymmetric (dis)similarity data. This visualization enables an intuitive interpretation of the asymmetry in (dis)similarity data.