Message-ID: <Pine.LNX.4.44.0301300737300.27042-100000@gannet.stats>
Date: 2003-01-30T08:43:03Z
From: Brian Ripley
Subject: print.default and attributes
In-Reply-To: <A8877251964B294BAB5BA1FC58B43FED025B44A4@molly.tas.csiro.au>
On Thu, 30 Jan 2003 Mark.Bravington@csiro.au wrote:
> When something gets printed by the "print.default" function, any extra
> attributes are printed without regard to their class attribute (if any). For
> example:
>
> > x <- 1:3
> > attr( x, 'other') <- factor( c( 'cat', 'dog'))
> > attr( x, 'other')
> [1] cat dog
> Levels: cat dog
> > x
> [1] 1 2 3
> attr(,"other")
> [1] 1 2
>
> which is perhaps surprising. Would it be preferable for "print.default" to
> call the generic "print" for each attribute, so that any class-specific
> print methods are respected?
That does seem unintentional, and not what S does.
> BTW, the same applies to "print.matrix" (which doesn't rely on "print"), and
> perhaps to other print methods. Of course, it will also apply to any
> class-specific print method which invokes "print" or "NextMethod", too.
In R-devel print.matrix *does* rely on print, and *is* a print method.
But the old-style prmatrix aka print.matrix does not print attributes
normally:
> x <- matrix(1:4, 2, 2)
> attr( x, 'other') <- factor( c( 'cat', 'dog'))
> prmatrix(x)
[,1] [,2]
[1,] 1 3
[2,] 2 4
So how did you make it print attributes?
--
Brian D. Ripley, ripley@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