Hi Jim thanks for the help. I think I understand all the steps you suggested. I tried an example with your code but there is something not working I think. See below.
all.filenames<-list.files(**path="pathtofile", full.names=TRUE) *#this step works* old.filenames<-read.table("**old.filenames.tab") *#this step works* filenames<-all.filenames[!(**all.filenames %in% old.filenames)]* ## I think the problem is here because all.filenames = filenames (also checked with str()), so I import all the files (old and new files added to my folder) each time I run the code.* write.table(all.filenames,**file="old.filenames.tab",row.**names=FALSE) *#this step works* Any suggestion? thanks again martin On Sun, Apr 21, 2013 at 6:30 PM, Jim Lemon <j...@bitwrit.com.au> wrote: > On 04/22/2013 05:36 AM, Martin Lavoie wrote: > >> Hi All >> >> I want to import several .dat files every day of the week from the same >> folder. >> >> Let say, on day 1, I have about 100 files in the folder. >> >> By using this code, everything works perfectly (maybe there is a more >> efficient way to do it): >> >> filenames<-list.files(path="**pathtofile", full.names=TRUE) >> library(plyr) >> import.list<- llply(filenames, read.table, header=TRUE, sep="", >> na.strings="NA", dec=".", strip.white=TRUE) >> # >> #MERGE and RESHAPE some of the files have different columns >> library(reshape) >> data3<- merge_recurse(import.list) >> # >> At the end of each day I will export the file as a cvs file in a different >> folder. >> >> My question is how can I import on day 2 (day3, day4, etc) the new files >> in >> the folder but without importing the files already imported from the >> previous days. >> >> Hi Martin, > Here is one method: > > # first set up a dummy file for the first run to avoid an error > system("echo xxx > old.filenames.tab") > # obviously don't do this again > all.filenames<-list.files(**path="pathtofile", full.names=TRUE) > old.filenames<-read.table("**old.filenames.tab") > filenames<-all.filenames[!(**all.filenames %in% old.filenames)] > write.table(all.filenames,**file="old.filenames.tab",row.**names=FALSE) > > library(plyr) > import.list<- llply(filenames, read.table, header=TRUE, sep="", > na.strings="NA", dec=".", strip.white=TRUE) > ... > > Jim > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org 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.