thank you very much for your reply. i studied the code you gave me and tried to make adjustments to fit the requirements that i need, thank you again.. i used the following codes:
> m <- read.table("D:/documents/5 stations/01014000.csv", sep =",") > z <- zoo(m[,4],as.Date(as.character(DF[,3]), "%m/%d/%Y")) > x <- aggregate(z, cut(time(z),"y"), max) i got the maximum values right using coredata(), my question now is, how can i call for the complete date (yyyy-mm-dd) and the year (yyyy) when the maximum observation for that year was observed? CJ Rubio wrote: > > hi everyone! > > hope you can help me here. > > i am a new R user. what i am trying to do is to find the maximum annual > discharge from a daily record. i have a data.frame which includes date and > the discharge. somewhat like this.. > > 10/1/1989 2410 > 10/2/1989 2460 > 10/3/1989 2890 > ... > ... > ... > 12/31/2005 5730 > > i have been browsing through the archives and fount out about the > aggregate function and the zoo package. here's one of the codes i've tried > > DF <- read.table(data[i], sep =",") ##i have several stations to > assimilate > Date <- as.Date(as.character(DF[,3]), "%m/%d/%Y") #the date is at the 3rd > column, obviously > library(zoo) > z <- aggregate(zoo(DF[,4]), cut(Date, "y"), max) > max.discharge <- coredata(z) > date <- time(z) > > the result should somehow look like this > 11/21/1926 32600 > 4/24/1927 66500 > ... > ... > .. > 4/26/2005 111000 > > thanks for your time reading my questions,, any suggestions will be truly > appreciated... > > > > -- View this message in context: http://www.nabble.com/annual-maximum-value-tp22049205p22051398.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.