'unclass' it first(assuming that it is POSIXct) -unclass(mytime)
On Mon, Feb 14, 2011 at 3:55 AM, JonC <jon_d_co...@yahoo.co.uk> wrote: > > I have a problem ordering by descending magnitude a POSIXt object. Can > someone help please and let me know how to work around this. My goal is to > be able to order my data by DATE and then by descending TIME. > > I have tried to include as much info as possible below. The problem stems > from trying to read in times from a CSV file. I have converted the character > time values to a POSIXt object using the STRPTIME function. I would like > ideally to sort using the order function as below. > > test.sort <- order(test$DATE, -test$mytime) > > However, when I try this I receive the error as below : > > Error in `-.POSIXt`(test2$mytime) : > unary '-' is not defined for "POSIXt" objects > > To make this easier to understand I have pasted my example data below with a > list of R commands I have used. Any help or assistance would be appreciated. > >> test2 <- read.csv("C:/Documents and Settings/Jonathan Cooke/My >> Documents/Downloads/test2.csv", sep=",") >> test2 > DATE TIME > 1 18/01/2011 08:00:01 > 2 18/01/2011 08:10:01 > 3 18/01/2011 08:20:01 > 4 18/01/2011 08:30:01 > 5 19/01/2011 08:00:01 > 6 19/01/2011 08:10:01 > 7 19/01/2011 08:20:01 > 8 19/01/2011 08:30:01 > >> test2$mytime <- strptime(test2$TIME,"%H:%M:%S") >> test2$mytime > [1] "2011-02-14 08:00:01" "2011-02-14 08:10:01" "2011-02-14 08:20:01" > "2011-02-14 08:30:01" "2011-02-14 08:00:01" > [6] "2011-02-14 08:10:01" "2011-02-14 08:20:01" "2011-02-14 08:30:01" > >> test2 > DATE TIME mytime > 1 18/01/2011 08:00:01 2011-02-14 08:00:01 > 2 18/01/2011 08:10:01 2011-02-14 08:10:01 > 3 18/01/2011 08:20:01 2011-02-14 08:20:01 > 4 18/01/2011 08:30:01 2011-02-14 08:30:01 > 5 19/01/2011 08:00:01 2011-02-14 08:00:01 > 6 19/01/2011 08:10:01 2011-02-14 08:10:01 > 7 19/01/2011 08:20:01 2011-02-14 08:20:01 > 8 19/01/2011 08:30:01 2011-02-14 08:30:01 > >> test2.sort <- order(test2$DATE, -test2$mytime) > Error in `-.POSIXt`(test2$mytime) : > unary '-' is not defined for "POSIXt" objects > > It's at this stage where I have got stuck as I'm new to R and don't yet know > a way of getting around this error. Thanks in advance. > > JonC > > > > > > > > > > -- > View this message in context: > http://r.789695.n4.nabble.com/how-to-order-POSIXt-objects-tp3304609p3304609.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. > -- Jim Holtman Data Munger Guru What is the problem that you are trying to solve? ______________________________________________ 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.