Thank you for your replies. That can be quite tricky indeed.
The data consists of monthly unemployment rates, which I get as a text
file along with the information: monthly, period of beginning and end.
So it does not come with some timestamp as I specify the time inside R.
This tweak time(X2) <- time(X2) + 6*60*60 does not work. However this
solves the problem:
time(X2)=as.POSIXct(time(X2))+6*60*60
But then each element in my series now show up with time too instead of
only year/month alone.
However Sys.setenv(TZ = "GMT") works perfectly for this purpose.
Thank you for your insights!
--
Philippe Baril Lecavalier
On 02/15/2012 11:30 PM, Gabor Grothendieck wrote:
On Wed, Feb 15, 2012 at 10:25 PM, P.B. Lecavalier<p.bar...@gmail.com> wrote:
Greetings,
I would like to subset observations in a time series using xts, after
converting from ts to xts.
X=ts(1:100, frequency=12, start=c(1976))
X2=as.xts(X)
X2["1984"]
The output:
Feb 1984 98
Mar 1984 99
Apr 1984 100
What happened to January? The index is always one month off, with
X2["1976-01"] giving me Feb 1976. Should I set the time using something else
than ts?
I know there is the window function, but the xts format is convenient for my
needs.
Any of these work with your sample data:
X2[ trunc(time(X2)) == 1984 ]
X2[ format(time(X2), "%Y") == "1984" ]
window(X2, start = 1984)
window(X, start = 1984)
Sys.setenv(TZ = "GMT")
X2["1984"]
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