Department of Statistics, University of California Riverside, Riverside, CA 92521, USA.|Molecular and Computational Biology Program, Departments of Biological Sciences, Chemistry, Physics, and Computer Science, University of Southern California, Los Angeles, CA 90089, USA.|Molecular and Computational Biology Program, Departments of Biological Sciences, Chemistry, Physics, and Computer Science, University of Southern California, Los Angeles, CA 90089, USA.|Department of Genome Sciences, Department of Computer Science and Engineering, University of Washington, Seattle, WA 98195, USA.