Thank you for your reply and the solution. Yes, I would like the date to be the column header for all the files in the list.
This is what tried following your suggestion; filelist = list.files(pattern = ".*.txt") date <- 20000101 for (file %in% filelist){ datalist <- read.table(file) write.table(datalist, file= file, col.names= date) } However, I get the following error Error: unexpected SPECIAL in "for (file %in%" Is it something silly I am missing? Thank you again! Best, Milu On Wed, Jan 20, 2021 at 1:29 AM <cpolw...@chemo.org.uk> wrote: > I'd use a for loop. But I may be misunderstanding the q! > > > filelist = list.files(pattern = ".*.txt") > date <- 20000101 > > for (file %in% filelist) { > > datalist <- read.table(file) > > write.table( datalist, file= file, col.names= date) > > } > > Does what I think you want. > I would actually write to a new filename (sub folder?) To avoid disaster! > > > > > > On 19 Jan 2021 23:45, Miluji Sb <miluj...@gmail.com> wrote: > > Dear all, > > I have more than 200 text files in a folder without header - example > below. > I would like to read, add a common date header to all the files, and write > (replace) the files. > > ## Read files > filelist = list.files(pattern = ".*.txt") > datalist = lapply(filelist, function(x)read.table(x, header=F)) > > ## What I want to add > date <- 20000101 > datalist _new <- lapply(datalist, function(x) rbind(x, date)) > > How do I add this date as a common header and replace the files? Any help > will be highly appreciated. Thank you. > > Best, > > Milu > > ## Sample data > xy <- dput(head(x,6)) > structure(list(V1 = c("-5.28082885742185,-0.509039307", > "-6.09873046874998,-0.349584961", > "-2.07150878906248,6.264276123", "-1.11102905273435,6.365716553", > "2.37749633789065,14.57106934", "4.9619079589844,18.91350708" > )), row.names = c(NA, 6L), class = "data.frame") > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. > > > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.