See tutorial on the Matlab version or R version.

Authors:

Tianchen Xu\(^{*}\),    tx2155@columbia.edu,    Department of Biostatistics, Mailman School of Public Health, Columbia University, NY 10032, USA

Ryan T. Demmer,    demm0009@umn.edu,    Division of Epidemiology, School of Public Health, University of Minnesota, MN 55454, USA

Gen Li,    gl2521@cumc.columbia.edu,    Department of Biostatistics, Mailman School of Public Health, Columbia University, NY 10032, USA