Choose a normalization method, there are three option currently.
Choose from "global.glsf", "ranked.glsf","spike.in" or no.norm, default = "ranked.glsf".
top.rank
If the method is set to "ranked.glsf", you need to set top number of genes sorted based on global base mean, default = 500.
spike.in.factors
A numeric vector of spike-in values with the same cell id order as the main data.
rpm.factor
If the norm.method is set to "rpm" the library sizes would be divided by this number, default = 1000 (higher numbers recomanded for bulk RNA-Seq).