skip columns in read.table without knowing how many columns

Question

So i know you can skip columns with read.table by providing a NULL to colClasses vector, but this is usually only helpful if you know how many columns are in your table.

What if I want to skip first 2 columns of table but read all the rest (which I know are numeric). Something like:

colClasses = c(NULL,NULL,rep("numeric", k))

except I don't know what k is. What would be best way to handle this?

Answer 1

If you use the default white-space separation on a file named "fil.txt" then use this

 colClasses = c(NULL,NULL,rep("numeric", count.fields("fil.txt")[1] -2 ))

If you use a different separator then something like

 colClasses = c(NULL,NULL,rep("numeric", count.fields("fil.txt", sep=",")[1] -2 ))

Answer 2

跳过前两列的简单方法：

data <- read.table("dataname.csv", header = TRUE, sep = ",")[,-c(1,2)]