Hi David, My initial reaction (not that the decision is mine to make), is that from a technical perspective, obviously indexing by name is common.
There are two considerations, off the top of my head: 1. There would be a difference, of course, between: > month.abb["1"] <NA> NA and > month.abb["01"] 01 "Jan" Thus, is this approach overly fragile and potentially going to create more problems (bugs, head scratching, etc.) than it solves. 2. From a consistency standpoint, I don't see an indication that other built-in constants have similar name attributes, not that I did an exhaustive review. So I suspect that if there were reasonable justification for it here, it would also need to at least be considered for other constants, which increases the scope of work a good bit. If there is a desire for this, one could file an RFE at https://bugs.r-project.org to gauge the reactions from R Core, unless they comment here first. Regards, Marc On Sep 23, 2014, at 12:47 PM, David Winsemius <dwinsem...@comcast.net> wrote: > Marc; > > Feature request: > > Would it make sense to construct month.abb as a named vector so that the > operation that was attempted would have succeeded? Adding alphanumeric names > c("01", "02", "03", "04", "05", "06", > "07", "08", "09", "10", "11", "12") would allow character extraction from > substring or regex extracted month values which are always character-class. > > Example: > >> names(month.abb) <- c("01", "02", "03", "04", "05", "06", > + "07", "08", "09", "10", "11", "12") >> month.abb > 01 02 03 04 05 06 07 08 09 10 11 12 > "Jan" "Feb" "Mar" "Apr" "May" "Jun" "Jul" "Aug" "Sep" "Oct" "Nov" "Dec" > > >> month.abb[ substr(Sys.Date(), 6,7) ] > 09 > "Sep" > > -- > David. > > On Sep 23, 2014, at 9:03 AM, Marc Schwartz 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. > > David Winsemius > Alameda, CA, USA > ______________________________________________ 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.