[R] lapply with argument "X"
Prof Brian Ripley
ripley at stats.ox.ac.uk
Wed Oct 6 18:33:32 CEST 2004
On Wed, 6 Oct 2004 john.gavin at ubs.com wrote:
> I am probably making a simple mistake but I can't see it
> > X
> Error: Object "X" not found
> > exists("X")
>  FALSE
> > lapply("X", exists)
>  TRUE
> Why is lapply producing true?
> Is it something to do with the first
> argument of lapply also being called 'X'?
Yes. Note that the first argument of lapply is supposed to be a list,
so what you are really using is
and indeed an object named "X" exists in the environment within which
exists() is run.
Brian D. Ripley, ripley at 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
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