Hi, in this self-contained example the file the same error message appears as when I read in my original results files.
library (zoo) library(chron) #generate example data Fish_ID=1646 Date <- "01/01/2004 00:01:00" Date <- as.POSIXct(strptime(Date,format="%m/%d/%Y %H:%M:%S")) R2sqrt <-100 #put into dataframe Test <- data.frame(Fish_ID=Fish_ID,Date=Date,R2sqrt=R2sqrt) # write .csv file write.csv(Test,file="Test") #generate list of files filenames="Test" #read file(s) into zoo object read.zoo(file=filenames, header = TRUE, FUN = as.chron, sep = ",", colClasses = c("NULL", "NULL", "character", "numeric")) #works fine #read list of files into zoo.object lapply(filenames, read.zoo, header = TRUE, FUN = as.chron, sep = ",", colClasses = c("NULL", "NULL", "character", "numeric"))# error "Error in strptime(x, format, tz = tz) : invalid 'x' argument" Am I missing something ? Thank you for your time and patience. Juliane Sorry for posting twice, libraries were missing earlier. ________________________________________ From: Gabor Grothendieck [ggrothendi...@gmail.com] Sent: 27 September 2010 23:32 To: Struve, Juliane Cc: r-help@r-project.org Subject: Re: [R] plotting multiple animal tracks against Date/Time On Mon, Sep 27, 2010 at 5:38 PM, Struve, Juliane <j.str...@imperial.ac.uk> wrote: > Hello, > > thank you very much for replying. The code yields an error message > > Error in strptime(x, format, tz = tz) : invalid 'x' argument > > But I can't see what's wrong with it, the Date/Time info is in the third > column, format is > "%Y-%m-%d %H:%M:%S". There is no time zone info in the data, could this be a > problem ? > See the last line on every message to r-help. You need to put together a minimal self contained example that illustrates the problem. The best I can do with the information provided is to point out that this works: > Lines <- '"","Fish_ID","Date","R2sqrt" + "1",1646,2006-08-18 08:48:59,0 + "2",1646,2006-08-18 09:53:20,100' > > library(zoo) > library(chron) > read.zoo(textConnection(Lines), header = TRUE, FUN = as.chron, + sep = ",", colClasses = c("NULL", "NULL", "character", "numeric")) (08/18/06 08:48:59) (08/18/06 09:53:20) 0 100 -- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.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.