File processing commands

Reading and writing csv files

 mydata = read.table("/share/data/expression.csv", head=TRUE, row.names = 1)
 write.table(mydata, "file", sep="\t")

Reading and writing excel files

 library(gdata)
 mydata <- read.xls("/share/data/expression.xls", sheet=1)

Read as matrix

 mydata <- as.matrix(read.xls("/share/data/expression.xls", sheet=1))