plot functions, formula interfaces and NAs
On Mon, 3 May 2004, Prof Brian Ripley wrote:
I believe no function should be using getOption("na.action") without a
means to override it, and thus the formula methods of
boxplot, mosaicplot and pairs
should get an na.action argument. Further, since in all cases the
non-formula methods do handle missing values, I think the default should
be na.pass. That is a change in behaviour, but the existing behaviour is
undocumented.
As I know Brian realises, but other people may not, it is not sufficient just to add na.action=na.pass as a default argument in a function that uses the usual match.call/eval.parent method to handle formulas. The default will be overridden by the default in model.frame. -thomas