Try this: library(gsubfn)
# convert date strings to dd-mm-yy Dates <- gsub("/", "-", dat$Dates) # regular expressiont to match dates re <- "\\d\\d-\\d\\d-\\d\\d" # extract dates and convert them to Date class # giving a list d each of whose components is a vector of dates d <- strapply(Dates, re, ~ as.Date(x, "%d-%m-%y"), perl = TRUE) names(d) <- dat$ID # combine them into a single data frame do.call(rbind, lapply(dat$ID, function(id) data.frame(ID = id, Date = d[[id]]))) On Fri, Mar 6, 2009 at 6:17 AM, bartjoosen <bartjoo...@hotmail.com> wrote: > > Hi, > > I have the following dataframe: > ID Dates > 1 16-07-01 06-10-95 > 2 24/01/02 06-10-95 > 3 16/01/02 16/08/94 12/01/91 > > And I would like to extract the dates, but couple the ID's to the right > dates, eg: > ID Dates > 1 16-07-01 > 1 06-10-95 > 2 24-01-02 > 2 .... > > I have no clue about how to get started, looks something for the > regexp/grep/... kind of functions, but I don't get the point. > > Any thoughts?? > > Kind regards > > Bart Joosen > > PS: for the reconstruction of the dataframe: > dat <- > structure(list(ID = c(1, 2, 3), Dates = structure(c(2L, 4L, 6L > ), .Label = c("16-01-02 16-08-94", "16-07-01 06-10-95", "24-01-02 > 06-10-95", > "24/01/02 06-10-95", "16/01/02 16/08/94", "16/01/02 16/08/94 > 12/01/91" > ), class = "factor")), .Names = c("ID", "Dates"), row.names = c(NA, > 3L), class = "data.frame") > > > -- > View this message in context: > http://www.nabble.com/Extract-dates-from-dataframe-tp22369479p22369479.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > 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. > ______________________________________________ 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.