See ?which.max : library(zoo) z <- read.zoo("myfile.dat", sep = ",", format = "%m/%d/%Y") f <- function(x) time(x)[which.max(x)] ix <- tapply(z, floor(as.yearmon(time(z))), f) z[ix]
On Tue, Feb 17, 2009 at 3:58 AM, CJ Rubio <cjru...@kongju.ac.kr> wrote: > > i have the following code - assimilating the maximum annual discharge each > year ffrom a daily discharge record from year 1989-2005. > > m <- read.table("D:/documents/5 stations/01014000.csv", sep =",") > z <- zoo(m[,4],as.Date(as.character(m[,3]), "%m/%d/%Y")) > x <- aggregate(z, floor(as.numeric(as.yearmon(time(z)))), max) #code > suggested by Gabor Grothendieck > > which gives me the maximum discharge each year and the year itself.. what i > am trying now is to produce the date when the maximum discharge was observed > in the pattern yyyy-mm-dd, like: > > 1988 11/9/1988 18600 > 1989 5/8/1989 49000 > ... > 2005 4/26/2005 111000 > > thank you all in advance... > -- > View this message in context: > http://www.nabble.com/problem-with-dates-in-zoo-package-tp22053103p22053103.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > 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.