On Fri, 2007-02-16 at 16:47 +0000, Prof Brian Ripley wrote: > On Fri, 16 Feb 2007, Marc Schwartz wrote: > > > On Fri, 2007-02-16 at 15:39 +0000, Sérgio Nunes wrote: > >> Just for the record, here are my steps for producing a date based > >> histogram. > >> Data is stored in a file where each line only has a date - 2007/02/16 > >> > >>> d<-readLines("filename.dat") > >>> d<-as.Date(d, format="%Y/%m/%d") > >>> pdf(yearly.pdf) > >>> hist(d, "years") > >>> dev.off() > >> > >> Instead of "years" you can also use "days", "weeks", "months", "secs", > >> "mins", "hours". > >> > >> One final question, how could I easily filter my dataset if, for > >> instance, I only wanted to see results from 2006 ? > >> > >> Thanks to all who helped, > >> Sérgio Nunes > > > > The easiest way may be to create your own "Year" extractor function, > > since there does not appear to be one by default, unless I missed it > > someplace (it is not listed in ?weekdays). > > >From that help page > > Note: > > Other components such as the day of the month or the year are very > easy to compute: just use 'as.POSIXlt' and extract the relevant > component. > > > 1900+as.POSIXlt(d2)$year > [1] 2006 2004 2004 > ...
Yes, indeed....and just as I was thinking that I had consumed a sufficient volume of coffee this morning... Thanks! Looking at the code for months() and weekdays(), for example: > months.Date function (x, abbreviate = FALSE) format(x, ifelse(abbreviate, "%b", "%B")) <environment: namespace:base> from a 'consistency' perspective, would it not make sense to have a years.Date() function along the same lines as what I had proposed? quarters() and julian(), of course, are appropriately different. Regards, Marc ______________________________________________ R-help@stat.math.ethz.ch 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.