Social Networks, Internet Traffic, Citation Networks, Transportation Networks, and Biological Networks exemplify real-world instances of unweighted directed graphs. Within these domains, the Graph Fourier Transform (GFT) serves as a fundamental tool for processing graph signals. Nonetheless, the asymmetry of adjacency matrices in directed graphs frequently hinders their diagonalizability, thus impeding the development of an appropriate GFT. Despite these challenges, extensive research endeavors have resulted in diverse approaches for GFT. To gauge their efficacy, access to real-world examples of unweighted directed graphs with publicly available datasets online would be exceptionally advantageous.

Q. Are there any real-world examples of (unweighted) directed graphs whose datasets are available on the web?