[R] problems with xlim in plot.zoo() and window()

[Gabor Grothendieck]

On Tue, May 29, 2012 at 11:47 AM, Agustin Lobo
<Agustin.Lobo at ictja.csic.es> wrote:
> I'm trying to get a minimally intuitive way of plotting zoo objects
> extracted for given periods of time
>
> I do:
>> plot(alyL32007z$NEE_st,col=cod,type="b",pch=18,xlim=time(alyL32007z)[c(3000,15000)])
>
> and get a  correct plot but the expression for xlim is hard to read by humans.
> I try
>> time(alyL32007z)[c(3000,15000)]
> [1] "2007-03-04 11:30:00 UTC" "2007-11-09 11:30:00 UTC"
>> plot(alyL32007z$NEE_st,col=cod,type="b",pch=18,xlim=c("2007-03-04 11:30:00 UTC" ,"2007-11-09 11:30:00 UTC"))
> Error in plot.window(...) : invalid 'xlim' value
>
> an error that makes sense, but then I try:
>> as.Date(c("2007-03-04 11:30:00 UTC" ,"2007-11-09 11:30:00 UTC"))
> [1] "2007-03-04" "2007-11-09"
>> plot(alyL32007z$NEE_st,col=cod,type="b",pch=18,xlim=as.Date(c("2007-03-04 11:30:00 UTC" ,"2007-11-09 11:30:00 UTC")))
>
> and get no error but an empty plot.
> How can I set xlim using a simple expression for given dates?
>
> I've also tried with window(), but:
>> delme <- window(alyL32007z, start = as.Date("2007-03-04"),end=as.Date("2007-11-09"))
> Warning messages:
> 1: In which(in.index & all.indexes >= start & all.indexes <= end) :
>  Incompatible methods ("Ops.POSIXt", "Ops.Date") for ">="
> 2: In which(in.index & all.indexes >= start & all.indexes <= end) :
>  Incompatible methods ("Ops.POSIXt", "Ops.Date") for "<="
>> str(delme)
> ‘zoo’ series (without observations)
>> delme <- window(alyL32007z, start = c(2007, 3), end = c(2007, 12))
>> str(delme)
> ‘zoo’ series (without observations)
>
> Is this a problem with the way I've made the dates? (using as.POSIXct())
>
> Data in http://dl.dropbox.com/u/3180464/alyL32007z.rda
> http://dl.dropbox.com/u/3180464/alyL32007.rda
> alyL32007z <- zoo(alyL32007[-1],alyL32007$time)

The code is attempting to use Date class with a series whose index is
not of Date class.


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