SummarizedExperiment（一）计算TPM

fpkmToTpm <- function(fpkm){
    exp(log(fpkm) - log(sum(fpkm)) + log(1e6))
}
f_fpkmToTpm <- function(l_e){
     apply(l_e,2,fpkmToTpm)
}
assay(sce, "TPM") <- f_fpkmToTpm(assay(sce, "HTSeq - FPKM"))