They are DirectKernels operating on DirectedGraphRepresentions.
Shortest Path Kernel
Java class: ShortestPathKernel
Source code: ShortestPathKernel.java
Maven Project: kelp-additional-kernels
JSON type: shortestPath
Description: it associates a feature to each pair of nodes of one graph. The feature name corresponds to pair of node labels while the value is the length of the shortest path between the nodes in the graph. Further details can be found in (Borgwardt and Kriegel, 2005).
Parameters:
- representation: the String identifying the representation on which the kernel must operate
Weisfeiler–Lehman Subtree Kernel
Java class: WLSubtreeMapper to manipulate the dataset instances and obtain the explicit vectors to be used by a LinearKernel
Maven Project: kelp-additional-kernels
Description: it is actually an explicit feature extractor that outputs vectors containing the features of the Weisfeiler–Lehman Subtree Kernel for Graphs (Shervashidze, 2011). A LinearKernel can be used to exploit the produced vectors.
References
K. M. Borgwardt and H.–P. Kriegel. Shortest–Path Kernels on Graphs. in Proceedings of the Fifth IEEE International Conference on Data Mining, 2005, pp. 74–81.
N. Shervashidze, Weisfeiler–lehman graph kernels, JMLR, vol. 12, pp. 2539–2561, 2011