将FPKM转换为TPM

$$TPM_i = \frac{X_i}{l_i}\times\frac{1}{\sum{\frac{X_j}{l_j}}}\times10^6$$

$$FPKM_i = \frac{X_i}{l_i\times\frac{N}{10^6}} = \frac{X_i}{l_iN}\times10^6$$

• $X_i$：Fragments of gene i

• $l_i$：Length of gene i (KB)

• N：Total fragments

$TPM_i = (\frac{X_i}{l_iN})(\frac{1}{\sum{\frac{X_j}{l_jN}}}) = \frac{FPKM_i}{\sum{FPKM_j}}$

# cols are samples and rows are gene features
TPM_mtx <- FPKM_mtx / rep(colSums(FPKM_mtx), each = nrow(FPKM_mtx)) * 1e6

参考

http://www.bio-info-trainee.com/2017.html