Map-based Algorithm Visualization with METAL Highway Data

We present the algorithm visualization capabilities of the METAL project. Using METAL's graph data which represents highway systems, a selection of interactive algorithm visualizations are performed. Progress of the algorithm is shown by changing the colors of the graph's vertices and/or edges overlaid on Google Maps and in color-coded tabular form, including contents of important data structures. Advantages include the real-world data set and the variety of data sizes available, enhancing student engagement. While many visualizations and visualization tools exist for graph and related algorithms, most focus on small, synthetic graphs. We describe our algorithm visualization capabilities, which include implementations of sequential search, graph traversals, Dijkstra's algorithm, and convex hulls. These can be executed on graphs ranging in size from a few vertices and edges to hundreds. We also present results of a survey of students who have used METAL's algorithm visualizations.