Hello everyone, I'm performing a RNA-seq analysis to understand the difference between 2 condition. I know I have data with batch effect and I know the batch "groups" (some samples were collected one day and the others another day). I know when the different samples where collected and I wanted to use the ComBat_seq function of sva to correct my raw reads matrix but the function returns me a large list and not a count matrix. Am I missing something? Here is the code I used, just to be sure I made everything right.

x <- read.table("raw_gene_counts.tsv",header=T,row.names=1)
head(x)

                OH86 OH92 OH98 OI04 OH87 OH93 OH99 OI05
ENSG00000000003   90  100   94  129   84  115   33  135
ENSG00000000005    0    0    0    1    0    0    0    0
ENSG00000000419  293  225  275  477  319  461  126  530
ENSG00000000457   79   64   53  107   73   99   23  135
ENSG00000000460   43   56   34   68   48   61   28   55
ENSG00000000938   13    5    8   14    9    6    2   13

batch <- as.factor(c("a", "a"; "b", "b"....))
x <- ComBat_seq(x, batch=batch, group=NULL, full_mod=FALSE)
head(x)

[[1]]
[1] 95

[[2]]
   [1] 0 0 0 0 0 0 1 0 0 0 0 0 2 2 0 1 1 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0
  [66] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 2 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1
 [131] 0 0 0 0 1 0 0 0 0 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
 [196] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0
 [261] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0
 [326] 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 1 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 2
 [391] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1
 [456] 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 2 0 0 0 0 1 0 0 0 1 0 0 0 0 0
 [521] 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0
 [586] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 1
 [651] 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
 [716] 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 2 0 0 0 0 1 0 0 0 0
 [781] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
 [846] 0 0 0 1 0 0 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
 [911] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
 [976] 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 2 1 0 0 0 0
 [ reached getOption("max.print") -- omitted 33030 entries ]

[[3]]
[1] 318

[[4]]
[1] 85

[[5]]
[1] 42

[[6]]
[1] 14

I also wanted to understand how the parameter "group" influences the outcome. Thanks everyone for the help

That happens if your x is a data.frame rather than a matrix. It is listed under the Q&A section in https://github.com/zhangyuqing/ComBat-seq starting with The function returns a list rather than the adjusted matrix.. It's questionable though why the developer do not throw a warning or x is a data.frame though, or just do the conversion to matrix internally.