1. Department of Statistics, Stanford University , Stanford, CA 94305, USA
2. Bio-X Program, Stanford University , Stanford, CA 94305, USA
3. College of Software, Nankai University , Tianjin 300350, China
4. Ministry of Education Key Laboratory of Bioinformatics, Bioinformatics Division at the Beijing National Research Center for Information Science and Technology, Center for Synthetic and Systems Biology, Department of Automation, Tsinghua University , Beijing 100084, China
5. Department of Biomedical Data Science, Stanford University , Stanford, CA 94305, USA