Mike, If depth is positive downward, you can simply plot its negative. Fir example, suppose you have a dataframe with ctd data:
> ctd[1,] id p t s 104613 5993512 2 25.248 36.238 > unique(ctd$id) [1] 5993512 3319148 3358648 3358538 3317809 3317562 3304786 3300555 3313863 [10] 3317901 3249908 3249987 If you are not fussy about the axis labels indicating negative values of pressure, you can plot them like this: xyplot(-p~t|factor(id), data=ctd, type="l", xlab="temperature (C)", ylab="pressure (dbar)") If you want to get rid of the minus signs: xyplot(-p~t|factor(id), data=ctd,type="l", xlab="temperature (C)", ylab="pressure (dbar)", scales=list(y=list(at=seq(-3000,0,by=500), labels=format(-seq(-3000,0,by=500))))) Hope this helps. Carlisle -- William Carlisle Thacker Atlantic Oceanographic and Meteorological Laboratory 4301 Rickenbacker Causeway, Miami, Florida 33149 USA Office: (305) 361-4323 Fax: (305) 361-4392 "Too many have dispensed with generosity in order to practice charity." Albert Camus > Subject: [R] Oceanographic lattice plots? > Date: Sat, 18 Oct 2003 14:14:14 -0400 > From: "Mike Prager" <[EMAIL PROTECTED]> > To: R Help List <[EMAIL PROTECTED]> > CC: Michael Prager <[EMAIL PROTECTED]> > > R 1.8.0 on Windows XP Professional. A huge THANK YOU to the R Team for > this marvelous software. > > I am making lattice plots of oceanographic data. The usual layout does not > conform to plotting conventions that marine scientists use when depth is > the independent variable. Under those conventions, plots are made with the > origin at the upper left, depth on the vertical axis (increasing as it goes > down), and the dependent variable on the horizontal axis (increasing to the > right). > > That convention has implications not just in how axes are labeled and set > up, but also when using smoothing routines such as panel.lowess(), because > the smoothed values are on the horizontal axis, not the vertical axis. > > Before I start looking at and modifying the R code that makes up the > relevant routines, I wonder if any reader has already developed R routines > for this purpose? > > -- > Michael Prager, Ph.D. > NOAA Beaufort Laboratory > Beaufort, North Carolina 28516 > http://shrimp.ccfhrb.noaa.gov/~mprager/ > *** > > ---------------------------------------------------------------------- > > Subject: Re: [R] Oceanographic lattice plots? > Date: Sat, 18 Oct 2003 13:29:14 -0500 > From: Deepayan Sarkar <[EMAIL PROTECTED]> > To: "Mike Prager" <[EMAIL PROTECTED]>, > R Help List <[EMAIL PROTECTED]> > CC: Michael Prager <[EMAIL PROTECTED]> > References: <[EMAIL PROTECTED]> > > On Saturday 18 October 2003 13:14, Mike Prager wrote: > > R 1.8.0 on Windows XP Professional. A huge THANK YOU to the R Team for > > this marvelous software. > > > > I am making lattice plots of oceanographic data. The usual layout does not > > conform to plotting conventions that marine scientists use when depth is > > the independent variable. Under those conventions, plots are made with the > > origin at the upper left, depth on the vertical axis (increasing as it goes > > down), and the dependent variable on the horizontal axis (increasing to the > > right). > > In case you decide to work on this yourself, this might be useful: > > Ideally, specifications like > > xyplot(depth ~ x, ylim = c(10, 0)) > > should reverse the y-axis direction. As pointed out some time back, this > doesn't work in lattice currently, but that should be fixed in the future (it > already works in my development version). > > > That convention has implications not just in how axes are labeled and set > > up, but also when using smoothing routines such as panel.lowess(), because > > the smoothed values are on the horizontal axis, not the vertical axis. > > These should be easy to modify. > > Deepayan > > > Before I start looking at and modifying the R code that makes up the > > relevant routines, I wonder if any reader has already developed R routines > > for this purpose? > > ---------------------------------------------------------------------- ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help