Dijkstra Algorithm
!!!Warning: experimental!!!
General Concept
The Dijkstra algorithm can be used to find the shortest path from a source node to a target node in a weighted graph with non-negative edge weights (see [2]).
The DijkstraGlobalLandMask class is creating a graph using the global land mask grid from the global-land-mask package. Each grid point (in the provided geographic bounding box) is a node in the graph and each node is connected to its (diagonal, horizontal and vertical) neighbors by an edge. The depth of neighbors can be specified using the DIJKSTRA_NOF_NEIGHBORS config variable. By default, only the direct closest neighbors are used (DIJKSTRA_NOF_NEIGHBORS=1). However, note that this might lead to non-optimal routes (the resulting route is not the shortest distance route) due to staircase effects! Thus, higher values of DIJKSTRA_NOF_NEIGHBORS are recommended which, on the other hand, will increase computation time and memory usage.
The path to the global land mask file has to be specified via DIJKSTRA_MASK_FILE. If the global-land-mask package is installed it is not necessary to download the file. The file should already be inside the package. You can check the path, e.g., with find ~ -type f -name globe_combined_mask_compressed.npz.
In the future, the framework could be expanded by integrating further graphs, especially non grid-generated graphs.