Re: [R] zooreg and window

From: Achim Zeileis <Achim.Zeileis_at_uibk.ac.at>
Date: Thu, 14 Apr 2011 22:40:39 +0200 (CEST)

On Thu, 14 Apr 2011, Katrina Bennett wrote:

> Hi Achim,
>
> Yes, this worked. I added the two strings
>
> regts.start <- as.Date(regts.start)
> regts.end <- as.Date(regts.end)
>
> and changed the frequency to 1 in my zooreg call.
>
> The window call now works perfectly.
>
> I'm still wrapping my head around POSIXct and ISOdatetime and how they
> need to be applied appropriately!

See

   Grothendieck & Petzoldt (2004). Date and Time Classes in R.    R News, 4(1), 29-32. http://www.R-project.org/doc/Rnews/

for a good introduction.

Also there was just a related JSS publication:

   Garrett Grolemund, Hadley Wickham (2011).    Dates and Times Made Easy with lubridate.    Journal of Statistical Software, 40(3), 1-25.    http://www.jstatsoft.org/v40/i03/.

Best,
Z

> Thank you,
>
> Katrina
>
> On Thu, Apr 14, 2011 at 12:26 AM, Achim Zeileis
> <Achim.Zeileis_at_uibk.ac.at> wrote:
>> On Wed, 13 Apr 2011, Katrina Bennett wrote:
>>
>>> Hello, I have a following time series data
>>>
>>> head(mend.dat)
>>>
>>> ID PARAM Year Month Day Value SYM
>>> 1 15052500     1 1965     5  15   128   A
>>> 2 15052500     1 1965     5  16   135   A
>>> 3 15052500     1 1965     5  17   157   A
>>> 4 15052500     1 1965     5  18   176   A
>>> 5 15052500     1 1965     5  19   198   A
>>> 6 15052500     1 1965     5  20   241   A
>>>
>>>
>>> I have loaded these data into as a zooreg object. The entire time
>>> series runs from 1965-05-15 until 2010-12-31.
>>>
>>> I have generated dates using ISOdatetime.
>>>
>>> regts.start <- ISOdatetime(year.start, mo.start, day.start, hour=0,
>>> min=0, sec=0, tz="GMT")
>>> regts.end <- ISOdatetime(year.end, mo.end, day.end, hour=0, min=0,
>>> sec=0, tz="GMT")
>>
>> Here, you use "POSIXct" for your time index, below in the window() call you
>> use "Date". The latter is more appropriate here because you appear to have
>> daily data (and not intraday data).
>>
>> Thus, you can do
>>
>> regts.start <- as.Date(regts.start)
>>
>> or create it from scratch via
>>
>> regts.start <- as.Date("1965-05-15")
>>
>> and analogously for regts.end.
>>
>> The deltat in the zooreg() call is then simply 1.
>>
>>> Then, I generate a zoo time series from the data.
>>>
>>> zts <- zooreg(mend.dat$Value, start = regts.start, end = regts.end,
>>> frequency = 1, deltat = 86400)
>>>
>>> I now want to subset using window.
>>>
>>> window(zts, start=as.Date("2000-01-01"), end=as.Date("2000-01-02"))
>>>
>>> This results in the following error message.
>>>
>>>
>>> Data:
>>> factor(0)
>>> 1496 Levels:  100 1000 10000 101 1010 10100 102 1020 103 1030 104 1040
>>> 105 1050 10500 106 1060 107 1070 108 1080 ... Eqp
>>>
>>> Index:
>>> character(0)
>>> Warning messages:
>>> 1: In which(in.index & all.indexes >= start & all.indexes <= end) :
>>>  Incompatible methods ("Ops.POSIXt", "Ops.Date") for ">="
>>> 2: In which(in.index & all.indexes >= start & all.indexes <= end) :
>>>  Incompatible methods ("Ops.POSIXt", "Ops.Date") for "<="
>>>
>>>
>>> Why is this happening?
>>>
>>> Thanks for your help.
>>>
>>> Katrina Bennett
>>>
>>> ______________________________________________
>>> R-help_at_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.
>>>
>>
>
>
>
> --
> Katrina E. Bennett
> PhD Student
> University of Alaska Fairbanks
> International Arctic Research Center
> 930 Koyukuk Drive, PO Box 757340
> Fairbanks, Alaska 99775-7340
> 907-474-1939 office
> 907-385-7657 cell
> kebennett_at_alaska.edu
>
>
> Personal Address:
> UAF, PO Box 752525
> Fairbanks, Alaska 99775-2525
> bennett.katrina_at_gmail.com
>



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