A fast heuristic for hierarchical Manhattan layout

Abstract

A fast heuristic for the layout of directed graphs according to Manhattan convention is presented. Nodes are placed into layers. Edges consist of sequences of vertical and horizontal segments. Sharing of segments is allowed in certain situations. The algorithm is an extension of the hierarchical layout method [11, 15] that includes crossing reduction and emphasis on a uniform edge orientation. Compared to the original algorithm, the time overhead is O(n + ek) where n, e and k are the number of nodes, of edges, and the maximal number of line rows between two layers of nodes. It produces drawings where each edge has at most four bends.