Intro

Networks often include a categorical link-type variable, and it can be useful to visually distinguish between links of different types.

In a node-link diagram, each node is represented by a line, and link-type can be visually encoded as color, line thickness, or line dashing style.

In an adjacency matrix, all links between a pair of nodes are represented by a single matrix cell. If there are links of multiple types between a pair of nodes, then this must be represented somehow.

The dataset in these examples is based on Figure 4 of Visual Encodings for Networks with Multiple Edge Types (pdf).