Hello, Is it just a columns names issue? Try (DF is your data, 'A' or other data.frame)
# colNames <- colnames(DF) colNames <- c("name", "publish day", "2011-01-01", "2011-01-02", "2011-01-03", "2011-01-04", "2011-01-05") x <- as.Date(colNames[-(1:2)]) x [1] "2011-01-01" "2011-01-02" "2011-01-03" "2011-01-04" "2011-01-05" y <- difftime(x[-1], x[1], units="days") y <- as.integer(y) y [1] 1 2 3 4 colNames[3] <- "D-Day" colNames[-(1:3)] <- paste("D", y, sep="+") colNames [1] "name" "publish day" "D-Day" "D+1" "D+2" [6] "D+3" "D+4" # colnames(DF) <- colNames Hope this helps, Rui Barradas -- View this message in context: http://r.789695.n4.nabble.com/macro-function-tp4427385p4429055.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.