Is there a way to read a file one line at a time? My file is potentially very large (multiple gigabytes) so I'd like to read and process one line at a time. The only choices I see are: 1) Direct the file to standard input and use readline(), but then I have to parse the data columns myself. 2) Call scan() with nlines=1 over and over again, incrementing skip, but I suspect that it will read the whole file each time. Any suggestions? -- Terry J. Westley, Software Systems Engineering Supervisor Veridian Engineering, Calspan Operations P.O. Box 400, Buffalo, NY 14225 twestley at buffalo.veridian.com http://www.veridian.com -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
"Terry Westley" <twestley at buffalo.veridian.com> writes:> Is there a way to read a file one line at a time? > My file is potentially very large (multiple gigabytes) > so I'd like to read and process one line at a time. > > The only choices I see are: > > 1) Direct the file to standard input and use readline(), > but then I have to parse the data columns myself. > > 2) Call scan() with nlines=1 over and over again, incrementing > skip, but I suspect that it will read the whole file each > time. > > Any suggestions?Somewhere in the attic of my mind lies a plan to implement something similar to the streams datatype of S4, but I don't think it will happen soon. I think the expedient way is to write a trio of short C routines for dyn.loading and R wrappers: OpenFile, GetLine, CloseFile. -- O__ ---- Peter Dalgaard Blegdamsvej 3 c/ /'_ --- Dept. of Biostatistics 2200 Cph. N (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._