When it converts the time to Date it does it relative to the GMT time zone, not your time zone. When its July 1st in your time zone it can be June 30th in the GMT time zone.
See the article in R News 4/1 Help Desk, and the table at the end of the article in particular, on ways to handle this. On 9/23/05, Vittorio <[EMAIL PROTECTED]> wrote: > Dear All, > I'm happily extracting data of temperature from an oracle db > under R via RODBC. After manipulating the extracted data I put them > into a data.frame 'dati' which is as follows: > > > dati > DATA tm. > UDINE/RIVOLTO tm.TORINO/CASELLE > 1 2005-07-01 > 22.35 23.80 > 2 2005-07-02 22.70 > 22.85 > 3 2005-07-03 23.80 24.30 > 4 2005-07- > 04 23.80 25.40 > .......... > > and > > > str(dati) > `data.frame': 11 obs. of 3 variables: > $ DATA :'POSIXct', > format: chr "2005-07-01" "2005-07-02" "2005-07-03" "2005-07-04" ... > $ > tm.UDINE/RIVOLTO : num 22.4 22.7 23.8 23.8 21.8 ... > $ tm. > TORINO/CASELLE: num 23.8 22.9 24.3 25.4 21.8 ... > - attr(*, > "reshapeWide")=List of 5 > ..$ v.names: NULL > ..$ timevar: chr "NOME" > ..$ idvar : chr "DATA" > ..$ times : Factor w/ 2 levels > "TORINO/CASELLE",..: 2 1 > ..$ varying: chr [1, 1:2] "tm.UDINE/RIVOLTO" > "tm.TORINO/CASELLE" > > > > You see that the first field DATA is POSIXct > > Now > > dati[1,1] > [1] "2005-07-01 ora solare Europa occidentale" > > BUT > > > > as.Date(dati[1,1],"%d%m%Y") > [1] "2005-06-30" > > How come? > What is wrong > with it (or better with me)? > > Ciao > Vittorio ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
