[R] plotting multiple animal tracks against Date/Time

[Struve, Juliane]

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 at gmail.com]
Sent: 29 September 2010 00:09
To: Struve, Juliane
Cc: r-help at 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 at 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.



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