Using dogesr to check Venetian social networks before and after the Serrata

Introduction

Using data from dogesr (Merelo-Guervós 2022), we will, in this vignette, analyze the change of the social network before and after the Serrata (Puga and Trefler 2014), revealed as a watershed event in the analysis performed in (Merelo 2023)

Set up

The main events that led to the Serrata happened during the government of the doge Pietro Gradenigo. Let’s check the effect of that event in the social netWe will then create two networks, one including that doge, the next one with all the others

library(dogesr)
library(igraph)

pre.serrata <- marriage.graph.slice(to="Pietro Gradenigo")
post.serrata <- marriage.graph.slice(from="Marino Zorzi")

Social networks pre and post-Serrata

This will call the function that creates, from raw data, the igraph data structure with which we can work. We still need to simplify them to be able to work with it.

weightify <- function( a.graph ) {
  other.graph <- a.graph
  E(other.graph)$weight <- 1
  other.graph <- simplify(other.graph, edge.attr.comb=list(weight="sum"))
  return(other.graph)
}
pre.serrata <- weightify(pre.serrata)
post.serrata <- weightify(post.serrata)

V(pre.serrata)$EV <- unname(unlist(eigen_centrality(pre.serrata)$vector))
V(post.serrata)$EV <- unname(unlist(eigen_centrality(post.serrata)$vector))
plot(pre.serrata,vertex.size=V(pre.serrata)$EV, layout=layout_nicely, vertex.label.cex=0.7)

plot(post.serrata,vertex.size=V(post.serrata)$EV, layout=layout_nicely, vertex.label.cex=0.7)

The pre-Serrata graph is on the top, the post-serrata on the bottom. Before the Serrata, there were small (up to 4-5) sets of connected components, the biggest one the “star” around the Tiepolo family (which was an important part of the early XIV century rebellion); however, the Serrata had the effect of connecting the network, mainly because there were many more doges per generation (as explained in (Merelo 2023)), but also because marrying became an tactical move to increase the reach of the social network.

It should be noted, however, that doges’ marriages were but a small part of the complete Venetian social network; however, it is an important sample that, besides, shows who arrived to the summit of power (or servitude to the state, depending on how you look at it).

Conclusions

Charting the doges social networks enables insights on the power and social dynamics of the Republic of Venice; being able to look at temporal slices is especially interesting since we can check how certain events influenced the social network.