On Tue, Jul 24, 2012 at 1:36 PM, Fred G <bayespoker...@gmail.com> wrote: > Hi-- > > I have three columns in an input file: > MONTH QUARTER YEAR > 2012-07 2012-3 2012 > 2001-07 2001-3 2001 > 2002-01 2002-1 2002 > > I want to make output like so: > MONTH QUARTER YEAR > 07 3 2012 > 07 3 2001 > 01 1 2002 >
Normally there is no need to store components of the date. Its usually easier to just extract what you need on the fly. Since you only seem to need the year, quarter and month if DF is your data frame you can store the date as a yearmon class object which is rich enough to contain everything else so you don't really need the MONTH, QUARTER and YEAR columns making everything simpler. library(zoo) ym <- as.yearmon(DF$MONTH) Now the year, quarter and month are: floor(ym) format(as.yearqtr(ym), "%q") format(ym, "%m") The last two return character strings which is likely ok but if you need them as numeric then use as.numeric(format(ym, "%m")) and similarly for the quarter. This does not involve regular expressions or intricate character manipulation. -- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.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.