Re: [Rd] Warning when indexing data.frame with FALSE

From: Prof Brian Ripley <ripley_at_stats.ox.ac.uk>
Date: Mon 31 Jul 2006 - 11:58:56 GMT

On Mon, 31 Jul 2006, hadley wickham wrote:

> Sorry, a better example is:
>
> > data.frame(a=1)[FALSE]
> NULL data frame with 1 rows
> > data.frame(a=1)[NULL]
> NULL data frame with 1 rows
>
> vs
>
> > data.frame()[FALSE]
> Warning in is.na(nm) : is.na() applied to non-(list or vector)
> NULL data frame with 0 rows
> > data.frame()[NULL]
> Warning in is.na(nm) : is.na() applied to non-(list or vector)
> NULL data frame with 0 rows

It's reasonable:

> names(data.frame())
NULL which is a problem as data frames are supposed to have names. So the bug is in data.frame.

-- 
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

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