答复: [R] How to draw x-axis time label.
Prof Brian Ripley
ripley at stats.ox.ac.uk
Mon Oct 18 12:18:01 CEST 2004
On Mon, 18 Oct 2004, Ivy_Li wrote:
> Thank you for helping me!
> I try the "pretty" funtion to select the x-axis position value.Then I use the "format" funtion.
> xax.pos <- pretty(as.numeric(x$x.name))
> format(xax.pos,'%d %b %y')
> > xax.pos
>  1091600000 1091800000 1092000000 1092200000 1092400000 1092600000 1092800000
>  1093000000
> There are something wrong. I found the xax.pos has been changed to the
> number of second calculated since 1970 ,such as 1091600000. So this
> problem was not solved.
The problem is that _you_ changed this by the use of as.numeric. Why are
you changing a time to a number by as.numeric? And why are you calling a
time `name' -- it is rather confusing!
If you didn't do that, you would find that plot() by default does
sensible things, and calling axis.POSIXct will give you added control.
See its help page.
Brian D. Ripley, ripley at stats.ox.ac.uk
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
More information about the R-help