Hi:

This 'works' on the lapply end:

# Function to read one file from the list:
g <- function(x) read.zoo(file = x, header = TRUE, FUN = as.chron, sep =
",",
                         colClasses = c("NULL", "NULL", "character",
"numeric"))
# Apply to all files in list:
lapply(filenames, g)
[[1]]
(01/01/04 00:01:00)
                100

# Just to prove to myself that this works on a list of input files,

write.csv(Test,file="Test2")
write.csv(Test,file="Test3")
filenames <- c('Test', 'Test2', 'Test3')
lapply(filenames, g)
[[1]]
(01/01/04 00:01:00)
                100

[[2]]
(01/01/04 00:01:00)
                100

[[3]]
(01/01/04 00:01:00)
                100

Hope this helps,
Dennis

On Wed, Sep 29, 2010 at 4:52 AM, Struve, Juliane <j.struve@imperial.ac.uk>wrote:

> I will post the example again to see if its readable now. My question is
> why
> does read.zoo(file=filenames,....) work and  lapply(filenames,
> read.zoo,...) does not ? Since I am reading the same file in both statements
> I just do not know how to interpret "Error in strptime(x, format, tz = tz) :
> invalid 'x' argument".
>
> Thank you for all help.
>
> Juliane
>
>  library(chron)
>  library(zoo)
>  #Generate example file
>  Fish_ID=1646
>  Date <- "01/01/2004 00:01:00"
>  Date <- as.POSIXct(strptime(Date,format="%m/%d/%Y %H:%M:%S"))
>  R2sqrt <-100
>  Test <- data.frame(Fish_ID=Fish_ID,Date=Date,R2sqrt=R2sqrt)
>  write.csv(Test,file="Test")
>  #Read in example file
>  filenames="Test"
>  read.zoo(file=filenames, header = TRUE, FUN = as.chron, sep = ",",
> colClasses = c("NULL", "NULL", "character", "numeric"))
>  lapply(filenames, read.zoo, header = TRUE, FUN = as.chron, sep = ",",
> colClasses = c("NULL", "NULL", "character", "numeric"))
>
> ________________________________________
> From: Gabor Grothendieck [ggrothendieck@gmail.com]
> Sent: 29 September 2010 00:09
> To: Struve, Juliane
> Cc: r-help@r-project.org
> Subject: Re: [R] plotting multiple animal tracks against Date/Time
>
> On Tue, Sep 28, 2010 at 9:30 AM, Struve, Juliane
> <j.struve@imperial.ac.uk> wrote:
> >
> > 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.
>
> Self contained means anyone else can just copy your code and paste it
> into their session and see the error message you see.
>
> Its likely that your file does not contain what you think it does.
>
>
>
> --
> 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.
>

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