Just one other addition. If by monthly summary you mean a summary that has an entry for each year/month combo rather than just one entry for all Januaries, one entry for all Februaries etc. then try this which works in both the Date and chron cases:
aggregate(z, as.yearmon, mean) On Tue, Sep 8, 2009 at 11:36 PM, Gabor Grothendieck <ggrothendi...@gmail.com> wrote: > Try this: > > Lines <- "Date A B C D E > 1978-10-22 18 20.64 0.0 0.176 -1.76 > 1978-10-23 15 17.06 0.4 0.147 2.52 > 1978-10-24 3 7.588 0.0 0.068 -6.86 > 1978-10-25 9 11.491 0.0 0.102 -1.01 > 1978-10-26 13 14.98 1.4 0.130 1.26 " > > library(zoo); library(chron) > z <- read.zoo(textConnection(Lines), header = TRUE, FUN = as.chron) > aggregate(z, months, mean) > aggregate(z, years, mean) > > chron was used above to take advantage of the convenient months() > and years() functions that are available for it although it could be > done using Date class with only slightly more complexity: > > library(zoo) > z <- read.zoo(textConnection(Lines), header = TRUE) > aggregate(z, format(time(z), "%m"), mean) > aggregate(z, format(time(z), "%Y"), mean) > > Read the three zoo vignettes and the article on dates in R News 4/1 as well > as the references to that article. > > On Tue, Sep 8, 2009 at 11:23 PM, Subodh Acharya<shoeb...@gmail.com> wrote: >> Hello Everyone,I think this is a very simple problem, I have been struggling >> with it for a few days now. >> I have a 10-year daily data in the following format. >> >> >> Date A B C D E >> 1978-10-22 18 20.64 0.0 0.176 -1.76 >> 1978-10-23 15 17.06 0.4 0.147 2.52 >> 1978-10-24 3 7.588 0.0 0.068 -6.86 >> 1978-10-25 9 11.491 0.0 0.102 -1.01 >> 1978-10-26 13 14.98 1.4 0.130 1.26 >> >> I want to calculate the monthly and Annual average averages of A, B, C, D, >> and E, for the 10 years. >> >> I tried to use the xts package to convert the data into a time series object >> but was not able to even change it into the time series object. >> Any help would be highly appreciated >> >> Thank you in advance. >> >> -- >> Subodh Acharya >> University of Florida >> Gainesville, FL. >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> 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. >> > ______________________________________________ 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.