An implementation of the rank fusion method proposed by Baily, et al. Rank-Biased Centroids.
P. Bailey, A. Moffat, F. Scholer, and P. Thomas. 2017. Retrieval Consistency in the Presence of Query Variations. In Proc. SIGIR. 395-404. DOI: https://doi.org/10.1145/3077136.3080839