Message-Id: <199906161359.OAA25142@toucan.stats.ox.ac.uk>
Date: Wed, 16 Jun 1999 14:59:47 +0100 (BST)
From: Prof Brian Ripley <ripley@stats.ox.ac.uk>
Subject: Re: [R] R: question about vectors + for loop
To: wolters@ikp.uni-bonn.de
> X-Authentication-Warning: stat.math.ethz.ch: majordom set sender to
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> Date: Sat, 5 Jun 1999 19:51:57 +0100
> From: Guido Masarotto <guido@hal.stat.unipd.it>
> To: Maria Wolters <wolters@ikp.uni-bonn.de>
> Cc: r-help@stat.math.ethz.ch
> Subject: Re: [R] R: question about vectors + for loop
>
> On Sat, Jun 05, 1999 at 04:14:11PM +0200, Maria Wolters wrote:
> > a) is there a straightforward way of saying
> > for all factors f in a data frame {
> > any old function, e.g. max(f)
> > }
>
> I am not sure to understand completly the question. Anyway, if
> d is a data.frame, you can extract the factors in d using something
> like
> > d.only.factor <- d[,unlist(lapply(d,is.factor))]
> Then, you can use lapply again to apply a 'old function' to the
> columns of d.only.factor. However, keep in mind that max, sum and
> like are considered not meaningful for factor. So, if you really
> insist in computing the max of the d.only.factor columns
> (assuming that this make sense) you should use something like
> > lapply(d.only.factor, function(x) max(as.numeric(x)))
>
> If this sounds cryptic, look to the manual pages (e.g., ?lapply,
> ?unlist,...) and perhaps to some of the suggested reading
> listed in the FAQ (the recommended one is
> W. N. Venables and B. D. Ripley (1997),
> "Modern Applied Statistics with S-PLUS. Second Edition".
> Springer, ISBN 0-387-98214-0
> Third edition is forthcoming (Brian Ripley can be more precise)
> so my suggestion is to get a copy from a library, not from a book
> shop)
>
Due in early August, but the main differences relate to new versions of
S-PLUS. See
http://www.stats.ox.ac.uk/pub/MASS3
for details
> > b) how can you construct a new data frame d' from
> > a given data frame d which contains only rows
> > with [X=="A"] (x is a factor of d)?
> > I know there's an obvious way, but with 50+ columns,
> > that's a wee bit tedious :)
>
> d.XequaltoA <- d[d$X=="A",]
> should do the work. Easy, isn't it?
>
>
> > c) could it be possible that there's a bug in the implementation of
> > the Kolmogorov-Smirnov test?
>
> I suspect that you must try to be more specific (and maybe,
> fill a bug report (?bug.report))
>
> Hoping this can help.
>
> guido
>
>
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-- 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 272860 (secr) Oxford OX1 3TG, UK Fax: +44 1865 272595-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request@stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._