I have a file with 15 million lines (will not fit in memory). I also have a small vector of line numbers - the lines that I want to extract.
How can I read-out the lines in one pass?
I was hoping for a C function that does it on one pass.
The trick is to use connection AND open it before
con<-file('filename') open(con) read.table(con,skip=5,nrow=1) #6-th line read.table(con,skip=20,nrow=1) #27-th line ... close(con)
You may also try
scan, it is faster and gives more control.