Figure 2.

Shadow links. Shadow links provide compact, complete views for all of the edges incident on a node. These two subset views are taken from the Human_Interactome_May.sif network [15], and show the same first neighbors of POLR2A and POLR2E. The top image shows the standard mode view; every edge appears once. Note that although a prominent node label appears over the large contiguous set of edges associated with the right terminus of each node (to enhance readability), those are not all the edges incident on the horizontal node row line. There are also edges on the left that are more closely associated with the distal nodes for those edges. In contrast, the bottom image shows the shadow link mode; each edge is has a duplicate shadow link, so that each node in the edge pair can display a copy of the edge as part of a single, labeled node zone. This provides a complete inventory of the edges in one location, allowing direct visual comparison of the connectivity of multiple nodes. This particular view of all the edges is provided here just to clarify how the shadow links are situated in the network; note that the bundle of edges on the right side of the lower view are the shadow links connecting to nodes laid out in the rows below POLR2A and POLR2E. The actual default display policy for creating subset views when shadow links are active is to discard the leftmost (true) and rightmost (shadow) links.