[R] More on scan()

[Thomas Lumley]

On Thu, 19 Dec 2002 apjaworski at mmm.com wrote:

>
> Here is one way of doing this.
> (1) read the whole file in as a vector of strings one line at a time
>       x <- readLines("<path to your data file>")
> (2) find the position of the "@DATA" string in your vector
>       s <- which(x == "@DATA")
> (3) scan the file again skipping s lines
>       scan("<path to your data file>", skip=s, sep=",", ...)
>
> You may want to consider using read.table instead of scan - it has the skip
> parameter too.  Finally you could actually reuse x from (1) above by
> something like
>       x <- x[-(1:s])
>       loop through elements of x and use the strsplit command to extract
> numbers from each line
> I suspect that this would be more cumbersome and slower than re-reading the
> file skiiping s lines from the top.

A simpler  solution that doesn't involve rereading is to use a connection

   conn<-file("myfile.txt")
   open(conn)
   repeat({
	a.line <- readLines(conn,n=1)
	if (substr(a.line,1,6)=="@DATA") break
   })

   read.csv(conn)

   close(conn)


	-thomas

Thomas Lumley			Asst. Professor, Biostatistics
tlumley at u.washington.edu	University of Washington, Seattle