Carlos Hernandez wrote: > dear All, > i'm trying to calculate the number of Mondays, Tuesdays, etc that each > month within a date range has. I have time series data that spans 60 > months and i want to calculate the number of Mondays, Tuesdays, Wed, etc > of each month. (I want to control for weekly seasonality but my data is > monthly). > > Is there an easy way to to this in R? or is there a package i could use? > i did some quick search in the help files and R sites but could not find > any answers. > > i appreciate any hint you could give,
This is where POSIXlt objects are useful: > unlist(unclass(as.POSIXlt(ISOdate(1959,3,11)))) sec min hour mday mon year wday yday isdst 0 0 12 11 2 59 3 69 0 Which means that I was born on a Wednesday (wday==3) in March (mon==2) (some of the fields count from 0 and others, like mday, from 1; presumably some UNIX vendor back in the Stone Age got their implementation turned into a standard...). This allows you to do stuff like: > dd <- seq(Sys.Date(),as.Date("2009-3-11"),1) > dd <- as.POSIXlt(dd) > with(dd, table(mon,wday)) wday mon 0 1 2 3 4 5 6 0 2 2 2 2 3 3 3 1 4 4 4 4 4 4 4 2 2 2 2 2 1 1 1 which I think is pretty much what you were looking for. > thanks. > > Carlos > > ______________________________________________ > 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. -- O__ ---- Peter Dalgaard Ă˜ster Farimagsgade 5, Entr.B c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - (p.dalga...@biostat.ku.dk) FAX: (+45) 35327907 ______________________________________________ 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.