yep, it works! impressingly elegant. R seems worth to dig into the details. I'll try harder.
Thank You very much Peter -----Ursprüngliche Nachricht----- Von: Prof Brian Ripley [mailto:[EMAIL PROTECTED] Gesendet: Freitag, 25. August 2006 17:53 An: Marx Peter Cc: r-help@stat.math.ethz.ch Betreff: Re: [R] How to get back POSIXct format after calculating with hist() results On Fri, 25 Aug 2006, [EMAIL PROTECTED] wrote: > Hi, > > I have a casting/formatting question on hist.POSIXt: > > The histogram plot from POSIXct works perfect (with help of Prof. > Ripley -thanks!). When processing the hist(plot=FALSE) output and then > plotting the results over the x-axis (bins) coming from hist(), I lose > the date/time labels, getting instead integers displayed. > > Trying to cast the $breaks with as.POSIXct gives silly results with > StarTrek-like years. But you actually called as.POSIXct(as.Date()) on them, which was `silly'. class(login_bins$mids) <- class(logins$DateTime) should do the trick. > What is the proper way to get back the old YY-MM-DD hh:mm:ss labels ? > > Peter > > > > > str(logins) > `data.frame': 25792 obs. of 1 variable: > $ DateTime:'POSIXct', format: chr "2006-08-01 00:00:02" "2006-08-01 > 00:00:25" "2006-08-01 00:00:41" ... > > > login_bins<-hist(samples$DateTime, "hours", freq=TRUE,plot=FALSE) > > > str(login_bins) > List of 7 > $ breaks : num [1:337] 1.15e+09 1.15e+09 1.15e+09 1.15e+09 1.15e+09 > ... > $ counts : int [1:336] 6 10 45 25 40 87 257 356 309 214 ... > $ intensities: num [1:336] 0.000233 0.000388 0.001744 0.000969 > 0.001550 ... > $ density : num [1:336] 6.46e-08 1.08e-07 4.85e-07 2.69e-07 4.31e-07 > ... > $ mids : num [1:336] 1.15e+09 1.15e+09 1.15e+09 1.15e+09 1.15e+09 > ... > $ xname : chr "logins$DateTime" > $ equidist : logi TRUE > - attr(*, "class")= chr "histogram" > > ... Then I do some calculations with the login_bins$counts, resulting > in a new vector: > > >str(userabs) > int [1:336] 1 -3 34 39 68 127 347 641 844 943 ... > > When I now plot this y over the x-axis coming from the previous > histogram x-axis with > > >plot(login_bins$mids, userabs) > > I get the x-axis of labelled with the nums 1154400000, 1154800000... > (number of seconds since 1970 ?) > > Trying to convert this gives funny results. > > >as.POSIXct(as.Date(login_bins$mids[1])) > [1] "2568-10-12 02:00:00 W. Europe Daylight Time" > > > as.POSIXct(as.Date(login_bins$mids[2])) > [1] "2578-08-21 02:00:00 W. Europe Daylight Time" > > ______________________________________________ > R-help@stat.math.ethz.ch 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. > -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ R-help@stat.math.ethz.ch 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.