On Tue, 2007-05-15 at 16:02 -0700, Juan Pablo Lewinger wrote: > I need to read two different random lines at a time from a large > ASCII file (120 x 296976) containing space delimited 0-1 entries. > > The following code does the job and it's reasonable fast for my needs: > > lineNumber = sample(120, 2) > line1 = scan(filename, what = "integer", skip=lineNumber[1]-1, nlines=1) > line2 = scan(filename, what = "integer", skip=lineNumber[2]-1, nlines=1) > > > system.time(for (i in 50){ > + lineNumber = sample(120, 2) > + line1 = scan(filename, what = "integer", skip=lineNumber[1]-1, nlines=1) > + line2 = scan(filename, what = "integer", skip=lineNumber[2]-1, nlines=1) > + }) > > Read 296976 items > Read 296976 items > [1] 14.24 0.12 14.51 NA NA > > However, I'm wondering if there's an even faster way to do this. Is there?
You might want to take a look at this post by Jim Holtman from earlier in the year for some ideas: http://tolstoy.newcastle.edu.au/R/e2/help/07/02/9709.html HTH, Marc Schwartz ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.