Accelerated partial decoding in wavelet trees

A Wavelet Tree (WT) is a compact data structure which is used in order to perform various well defined operations directly on the compressed form of a file. As random access is one of these operations, the underlying file is not needed anymore, and is often discarded because it can be restored, when necessary, by repeated accesses. This paper concentrates on cases in which partial decoding of a contiguous portion of the file, or even its full decoding, is still needed. We show how to accelerate the decoding relative to repeatedly performing random accesses on the consecutive indices. Preliminary experiments on full decoding support the effectiveness of our approach, and present an improvement of about 60% of the run-time.