Below is an example where a layout algorithm works by laying out a disconnected graph normally (left) and uses this extension to pack components after layout (right). Often times a particular layout algorithm will nicely lay out individual components of a disconnected graph but will not properly pack these components with respect to each other. Hence these are exposed as user customizable options by the extension.Īnother utility available in this library is for placing / packing components of a disconnected graph. In all of the above cases, we try to choose a position which is an ideal edge length away from a neighbor, and use a random offset for the final location of the node to avoid multiple nodes ending up at the exact same location since most layout algorithms will not gracefully handle such cases. If a new node without layout has no neighbors with layout information, then we place it around the periphery of the bounding box of all nodes with up-to-date layout. If a new node without layout has multiple neighbors with layout information, we chose the position of the new node without layout to be the geometric center of all its neighbors. If a new node without layout has a single neighbor with layout information, the idea is to split the neighboring space around the single neighbor into quadrants and scoring how crowded each quadrant is, and placing the new node in the least crowded quadrant. When doing so, these methods use the following heuristics : However, often times, the new nodes do not have an initial position (or a good one) for incremental layout (randomize: false) to produce good results. Some utility methods in this library try to choose the best position for any node without a previous or outdated layout, so that subsequent incremental layout is a good one. Sometimes, your graph will have a pre-calculated layout but changes (addition and/or deletion of nodes and edges or simply changes in graph geometry) will require an incremental layout to adjust the existing layout according to these changes. This Cytoscape.js extension provides miscellenaous layout utilities in order to manage the placement of nodes or components without layout information.

Cytoscape space between nodes