ABSTRACT
This chapter explains design choices for arranging network data in space. The node-link diagram family of visual encoding idioms uses the connection channel, where marks represent links rather than nodes. The second major family of network encoding idioms is matrix views that directly show adjacency relationships. Tree structure can be shown with the containment channel, where enclosing link marks show hierarchical relationships through nesting. The most common visual encoding idiom for tree and network data is with node-link diagrams, where nodes are drawn as point marks and the links connecting them are drawn as line marks. This idiom uses connection marks to indicate the relationships between items. Networks are also very commonly represented as node-link diagrams, using connection. Nodes that are directly connected by a single link are perceived as having the tightest grouping, while nodes with a long path of multiple hops between them are less closely grouped.
