Before revision:  Recently, Gagie et al. presented r-index,  an efficient compressed index on RLBWT whose space usage does not depend on text length . In this paper , we present a new compressed index on RLBWT, which we call r-index-f, in which r-index is improved for faster locatequeries. in constant time with O(r) words of space, which is a bit step forward in computation time from the previous best result of O(\log \log n) time for string length n and O(r) words of space.
After revision:  Recently, Gagie et al. presented r-index, an efficient compressed index on RLBWT whose space usage depends not on string length but the number of runs in an RLBWT, and it supports locate queries in an optimal time with \omega(r) words for the number r of runs in the RLBWT of an input string. Following this line of research , we present a new compressed index on RLBWT, which we call r-index-f, in which r-index is improved for faster locatequeries. in constant time with O(r) words of space, which is a bit step forward in computation time from the previous best result of O(\log \log n) time for string length n and O(r) words of space.