This matrix diagram visualizes co-occurrence relationships among characters from Les Misérables, with rows and columns ordered and colored by community structure identified through Louvain modularity. Each cell’s color intensity reflects the frequency of character interactions, while light gray indicates no interaction. Rendered as an SVG using D3 v4, the diagram groups characters into colored communities along both axes, making clustered relationships readily apparent. Compared to node-link diagrams, which often become unreadable "hairballs" in dense networks, the matrix format is simpler and easier to scan—though its readability depends heavily on the ordering of rows and columns, and tracing multi-step paths between nodes is difficult. With very large graphs, fitting hundreds or thousands of labeled rows and columns on screen becomes a challenge. The data come from a JSON file of academic alumni, with nodes representing people and departments, edges representing affiliations, and communities determined by Louvain modularity.