Many thanks for your quick answer which has created what I wished. May I ask followup question on the same issue. I failed to convert the new column into date format with this code. The class of MonthDay is still character
df$MonthDay <- format(df$MonthDay, format=c("%b %Y")) I would appreciate if you could suggest a working solution Thanks On 23 September 2014 18:03, Marc Schwartz <marc_schwa...@me.com> wrote: > On Sep 23, 2014, at 10:41 AM, Kuma Raj <pollar...@gmail.com> wrote: > >> Dear R users, >> >> I have a data with month and year columns which are both characters >> and wanted to create a new column like Jan-1999 >> with the following code. The result is all NA for the month part. What >> is wrong with the and what is the right way to combine the two? >> >> ddf$MonthDay <- paste(month.abb[ddf$month], ddf$Year, sep="-" ) >> >> >> Thanks >> >>> dput(ddf) >> structure(list(month = c("01", "02", "03", "04", "05", "06", >> "07", "08", "09", "10", "11", "12"), Year = c("1999", "1999", >> "1999", "1999", "1999", "1999", "1999", "1999", "1999", "1999", >> "1999", "1999"), views = c(42, 49, 44, 38, 37, 35, 38, 39, 38, >> 39, 38, 46), MonthDay = c("NA-1999", "NA-1999", "NA-1999", "NA-1999", >> "NA-1999", "NA-1999", "NA-1999", "NA-1999", "NA-1999", "NA-1999", >> "NA-1999", "NA-1999")), .Names = c("month", "Year", "views", >> "MonthDay"), row.names = 109:120, class = "data.frame") >>> >> > > > > Since you are trying to use ddf$month as an index into month.abb, you will > either need to coerce ddf$month to numeric in your code, or adjust how the > data frame is created. > > In the case of the former approach: > >> paste(month.abb[as.numeric(ddf$month)], ddf$Year, sep="-" ) > [1] "Jan-1999" "Feb-1999" "Mar-1999" "Apr-1999" "May-1999" "Jun-1999" > [7] "Jul-1999" "Aug-1999" "Sep-1999" "Oct-1999" "Nov-1999" "Dec-1999" > > > Regards, > > Marc Schwartz > ______________________________________________ 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.