Hi all, this one left me a bit puzzled, as I don't seem to find a function to perform this easily. I must have overlooked the obvious, so sorry in advance. I have a list of dates in numerical format (i.e. 34576), defined as the number of days that passed since january 1st 1900. So I apply the function :> MyDate <-as.Date(34576,origin="1900-01-01") > MyDate[1] "1994-09-01" But then I want to do something like : MyYear <- a.year.function(MyDate) MyYear should have the numerical value 1994. Alas, I don't find any function like that. I know I can take a substring of MyDate and convert to numeric, or even use the function "seq()" :> length ( seq ( as.Date("1900-01-01"), MyDate, "years" ) ) + 1900 - 1[1] 1994 but that seems quite a way around. Can somebody tell me where the appropriate function is hiding? Thank you in advance. Joris
r-help-bounces at r-project.org napsal dne 06.10.2009 11:39:51:> Hi all, > > this one left me a bit puzzled, as I don't seem to find a function to > perform this easily. I must have overlooked the obvious, so sorry in > advance. > > I have a list of dates in numerical format (i.e. 34576), defined as > the number of days that passed since january 1st 1900. So I apply the > function : > > > MyDate <-as.Date(34576,origin="1900-01-01") > > MyDate > [1] "1994-09-01" > > But then I want to do something like : > MyYear <- a.year.function(MyDate) > > MyYear should have the numerical value 1994. Alas, I don't find any > function like that. I know I can take a substring of MyDate and > convert to numeric, or even use the function "seq()" : >E.g. as.numeric(format(MyDate, "%Y")) [1] 1994 Regards Petr> > length ( seq ( as.Date("1900-01-01"), MyDate, "years" ) ) + 1900 - 1 > [1] 1994 > > but that seems quite a way around. Can somebody tell me where the > appropriate function is hiding? > Thank you in advance. > Joris > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guidehttp://www.R-project.org/posting-guide.html> and provide commented, minimal, self-contained, reproducible code.
See ?weekdays, which says 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. so> as.POSIXlt(MyDate)$year+1900[1] 1994 is how you are expected to do it. On Tue, 6 Oct 2009, joris meys wrote:> Hi all, > > this one left me a bit puzzled, as I don't seem to find a function to > perform this easily. I must have overlooked the obvious, so sorry in > advance. > > I have a list of dates in numerical format (i.e. 34576), defined as > the number of days that passed since january 1st 1900. So I apply the > function : > >> MyDate <-as.Date(34576,origin="1900-01-01") >> MyDate > [1] "1994-09-01" > > But then I want to do something like : > MyYear <- a.year.function(MyDate) > > MyYear should have the numerical value 1994. Alas, I don't find any > function like that. I know I can take a substring of MyDate and > convert to numeric, or even use the function "seq()" : > >> length ( seq ( as.Date("1900-01-01"), MyDate, "years" ) ) + 1900 - 1 > [1] 1994 > > but that seems quite a way around. Can somebody tell me where the > appropriate function is hiding? > Thank you in advance. > Joris > > ______________________________________________ > R-help at 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. >-- Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595