Andy, It is surprising that scan() attempts to read anything at all: note that I set nmax=0, which AFAIK means read no lines.
Thank you for a reference to replicate(). I didn't know about it. Thanks, Vadim -----Original Message----- From: Liaw, Andy [mailto:[EMAIL PROTECTED] Sent: Saturday, May 01, 2004 5:28 PM To: Vadim Ogranovich; [EMAIL PROTECTED] Subject: RE: [R] skip lines on a connection Your scan() call doesn't work because default argument what=0; i.e., it expects numeric data. You probably can just use what="". The other alternative is to just loop readLines() n times, reading one line at a time. It probably won't be too bad in terms of time, and surely will save on memory usage. (Try using replicate().) HTH, Andy > From: Vadim Ogranovich > > Unfortunately, seek only works in terms of bytes not lines and I only > know how many lines I need to skip, but not bytes. > > > -----Original Message----- > From: Gabor Grothendieck [mailto:[EMAIL PROTECTED] > Sent: Saturday, May 01, 2004 3:44 PM > To: [EMAIL PROTECTED] > Subject: Re: [R] skip lines on a connection > > > > > ?seek > > Vadim Ogranovich <vograno <at> evafunds.com> writes: > > : > : Hi, > : > : I am looking for an efficient way of skipping big chunks of > lines on a > : connection (not necessarily at the beginning of the file). > One way is > to > : use read lines, e.g. readLines(1e6), but a) this incurs the overhead > of > : construction of the return char vector and b) has a (fairly remote) > : potential to blow up the memory. > : > : Another way would be to use scan(), e.g. > : > : scan(con, skip=1e6, nmax=0) > : > : but somehow this doesn't work: > : > : > scan(con, skip=10, nmax=0) > : Error in scan(con, skip = 10, nmax = 0) : > : "scan" expected a real, got "A;12;0;" > : > : I can stick to readLines, but am curious if there is a better way. > : > : I use R-1.8.1 on RH-7.3. > : > : Thanks, > : Vadim > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > > ------------------------------------------------------------------------ ------ Notice: This e-mail message, together with any attachments,...{{dropped}} ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
