[Rd] qqnorm(*, datax=TRUE, xlab,ylab) -- S+ compatibility problem

Martin Maechler maechler at stat.math.ethz.ch
Wed Oct 15 23:48:03 MEST 2003

Just found because an old (written for S+) function of mine did 
label plots wrongly with R.

Example --- inspired from  example(qqnorm) ---

  qqnorm(precip, ylab = "Precipitation [in/yr] ...")
  qqnorm(precip, ylab = "Precipitation [in/yr] ...", datax = TRUE)

this is all "fine" -- `datax' is a switch that just switches the
axes but keeps the meaning of "ylab labels the data axis"
(i.e, when changing datax from FALSE to TRUE, you don't have to
 switch xlab and ylab in your call).

Unfortunately,  S+ (6.1) does this differently, 
namely with the logic of  "ylab labels the y-axis",
i.e. the last line above would have to be written

  qqnorm(precip, xlab = "Precipitation [in/yr] ...", datax = TRUE)
  ##            _^_

for S+ to produce the same (well analogous) plot.

Since, the `datax' extension was only introduced for R 1.7.0,
NEWS>  o  qqnorm() and qqline() have an optional logical argument
NEWS> 	  `datax' to transpose the plot (S-PLUS compatibility).
we could consider changing R's behavior here 
--- unfortunately not back-compatibly.


Martin Maechler <maechler at stat.math.ethz.ch>	http://stat.ethz.ch/~maechler/
Seminar fuer Statistik, ETH-Zentrum  LEO C16	Leonhardstr. 27
ETH (Federal Inst. Technology)	8092 Zurich	SWITZERLAND
phone: x-41-1-632-3408		fax: ...-1228			<><

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