Since the original work of Moreno (1934), network data has become ubiquitous in computational social sciences (Snijders and Nowicki, 1997). Applications range from the study of social interactions in historical sciences (Jernite et al., 2014; Villa et al., 2008) to the analysis of maritime flows in geography (Ducruet, 2013). In particular, network analysis was applied recently to a medieval social network in Jernite et al. (2014), where the authors consider the clustering of an ecclesiastical network in Merovingian Gaul. Cluster analysis in the network context consists in grouping vertices sharing homogeneous connection profiles.