On 12 May 2015, at 16:34 , Bob O'Hara <rni....@gmail.com> wrote: > I'm helping colleagues with analysis of frog calls at night,
What do you do during the daytime then? > and they > want to plot call statistics against time. This means we hit a > problem: we want the x-axis to start at (say) 18:00 and end at (say) > 06:00. I'm reluctant to use the date as well, because we have data > from several dates, but only want to plot against time of day. > > Here's some code to illustrate the problem (don't worry about the data > being outside the range of the plot: this is only for illustration). > > library(chron) > Times <- chron(times.=paste(c(18:23,0:9),":30:00", sep="")) > Thing <- rnorm(length(Times)) # just something for the y-axis > > plot(Times,Thing) # x-axis wrong > plot(Times,Thing, xlim=chron(times.=c("05:00:00", "18:00:00"))) # x-axis right > plot(Times,Thing, xlim=chron(times.=c("18:00:00", "05:00:00"))) # > would like this to work... > > Can anyone suggest a solution? It may be sheer luck, but this seems to work OK: > Times <- as.POSIXct("1970-01-01 18:00", > tz="UTC")+as.difftime(seq(0,12,.5),units="hours") > Things<-rnorm(25) > plot(Times,Things) I think the chron route is doomed because of the fundamental confusion between going backwards in time and crossing midnight. With a little diligence you should be able to shift dates to a common origin. -pd > > Bob > > -- > Bob O'Hara > > Biodiversity and Climate Research Centre > Senckenberganlage 25 > D-60325 Frankfurt am Main, > Germany > > Tel: +49 69 798 40226 > Mobile: +49 1515 888 5440 > WWW: http://www.bik-f.de/root/index.php?page_id=219 > Blog: http://occamstypewriter.org/boboh/ > Journal of Negative Results - EEB: www.jnr-eeb.org > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. -- Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Office: A 4.23 Email: pd....@cbs.dk Priv: pda...@gmail.com ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.