The help page means exactly what it says, but the English is too subtle and I have reworded it.
I have no idea why you are interested in pairlists (they are hardly used at user-visible level these days). The point is that pairlist() is NULL and so strictly not a pairlist at all (try typeof() on it). However, is.pairlist(NULL) is true for historical reasons. On Fri, 14 Oct 2005, ronggui wrote: > the help page says: > > 'is.list' returns 'TRUE' iff its argument is a 'list' _or_ a > 'pairlist' of 'length' > 0, whereas 'is.pairlist' only returns > 'TRUE' in the latter case. > > does the "latter case" mean a 'pairlist' of 'length' > 0? > > but >> is.pairlist(pairlist()) > [1] TRUE >> length(pairlist()) > [1] 0 > > what the help page exactly means? > > 2005-10-14 > > ------ > Deparment of Sociology > Fudan University -- Brian D. Ripley, [EMAIL PROTECTED] 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 ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
