You need to convert to POSIXct since POSIXlt is a vector of size 9. So do the following:
miedate <- as.POSIXct(strptime(as.character(pressione[,1]), format="%d-%m-%Y %H:%M:%S")) There is a newsletter (I forget the issue) that you might want to refer to on using 'dates'. On 2/21/08, vittorio <[EMAIL PROTECTED]> wrote: > In the text file pressione2008.csv I have the following > > "Data","MAX","MIN","Note" > "07-01-2008 08:00:00", 135, 90, "Eccessi feste, inizio dieta" > "07-01-2008 18:00:00", 135, 85, "" > "08-01-2008 08:00:00", 125, 75, "" > > which is a collection of blood pressure data at different time of the day. > I would like to build an its with MIN & MAX blood pressure but being a real > newbye with zoo I obtain the following > > > library(zoo) > pressione <- data.frame(read.csv("pressione2008.csv")) > > miedate <- strptime(as.character(pressione[,1]), format="%d-%m-%Y %H:%M:%S") > > > miedate > [1] "2008-01-07 08:00:00" "2008-01-07 18:00:00" "2008-01-08 08:00:00" > > > str(miedate) > POSIXlt[1:9], format: "2008-01-07 08:00:00" "2008-01-07 18:00:00" ... > > > ts<- as.zoo(matrix(pressione[,2:3],ncol=2), miedate) > > ts > Error in Ops.POSIXt(freq, d) : * not defined for "POSIXt" objects > > > ts<- zoo(matrix(pressione[,2:3],ncol=2), miedate) > Error in order(x, ..., na.last = na.last, decreasing = decreasing) : > unimplemented type 'list' in 'orderVector1' > In addition: Warning message: > In zoo(matrix(pressione[, 2:3], ncol = 2), miedate) : > some methods for "zoo" objects do not work if the index entries > in 'order.by' are not unique > > > > > Please help > > Ciao > Vittorio > > ______________________________________________ > 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 Cincinnati, OH +1 513 646 9390 What is the problem 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.