Hello Tom, try aggregate() or cast(). Both works.I prefer the latter.
library(reshape) desc<-melt(mydata, measure.vars=c("WDI","R.WSP", "D.GST", "PRES", "ATMP", "DEWP"), id.vars=c("X.YY","MM","DD")) summary<-cast(desc, X.YY+MM+DD~variable, mean) On 17 July 2016 at 06:22, Tom Mosca <t...@vims.edu> wrote: > Hello Good Folk, > > My dataframe looks like this: >> mydata > X.YY MM DD hh WDI R.WSP D.GST PRES ATMP DEWP > 1 2015 1 1 0 328 3.6 4.5 1028.0 3.8 -3.5 > 2 2015 1 1 1 300 2.1 2.7 1027.9 3.7 -4.4 > 3 2015 1 1 2 264 2.4 2.9 1027.7 3.6 -4.5 > 4 2015 1 1 3 230 4.1 4.5 1027.4 4.2 -3.8 > 5 2015 1 1 4 242 8.1 9.2 1026.6 4.4 -3.1 > 6 2015 1 1 5 262 9.3 10.1 1026.6 4.1 -3.8 > 7 2015 1 1 6 267 8.6 9.6 1026.3 4.2 -3.8 > 8 2015 1 1 7 264 9.3 9.9 1026.1 3.9 -2.8 > 9 2015 1 1 8 268 8.2 9.1 1026.1 3.5 -3.0 > 10 2015 1 1 9 272 8.8 9.6 1025.4 3.2 -3.3 … > > The first four columns are year, month, day, hour (0 – 23). I wish to take > the means of the next six columns (WDIR, WSPD, GST, PRES, ATMP and DEWP) by > year, month and day. That is, I want daily averages. > > Please help. Thank you. > > Tom > > [[alternative HTML version deleted]] > > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. -- Jianling Fan 樊建凌 ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.