From ripley at stats.ox.ac.uk  Wed May  5 07:57:06 2004
From: ripley at stats.ox.ac.uk (Prof Brian Ripley)
Date: Wed May  5 07:57:13 2004
Subject: [Rd] Segfault from knn.cv in class package (PR#6856)
In-Reply-To: <20040505015338.402ABEDF3@slim.kubism.ku.dk>
Message-ID: <Pine.LNX.4.44.0405050653040.9946-100000@gannet.stats>

This is user error.

R-bugs is not the appropriate place to report user error in a contributed 
package -- please do read the R FAQ.

On Wed, 5 May 2004 jmacdon@med.umich.edu wrote:

> The function knn.cv in the class package doesn't have error checking to
> ensure that the length of the classlabel argument is equal to the number
> of rows in the test set. If the classlabel is short, the result is often

There is no *test* set in knn.cv, nor is there a `classlabel argument'.
There is 

      cl: factor of true classifications of training set 

and that has been specified incorrectly.

> a segfault.
> 
> > library(class)
> > dat <- matrix(rnorm(1000), nrow=10)
> > cl <- c(rep(1,5), rep(2,5))
> > cl2 <- c(rep(1,5), rep(2,4))
> > knn.cv(dat, cl)
>  [1] 2 2 1 2 1 2 2 2 2 2
> Levels: 1 2
> > knn.cv(dat, cl2) # May have to try more than once to get segfault.
> 
> This also occurs on my linux box.
> 
> Best,
> 
> Jim
> 
> 
> 
> --please do not edit the information below--
> 
> Version:
>  platform = i386-pc-mingw32
>  arch = i386
>  os = mingw32
>  system = i386, mingw32
>  status = 
>  major = 1
>  minor = 9.0
>  year = 2004
>  month = 04
>  day = 12
>  language = R
> 
> Windows XP Professional (build 2600) Service Pack 1.0
> 
> Search Path:
>  .GlobalEnv, package:methods, package:stats, package:graphics,
> package:utils, Autoloads, package:base
> 
> 
> James W. MacDonald
> Affymetrix and cDNA Microarray Core
> University of Michigan Cancer Center
> 1500 E. Medical Center Drive
> 7410 CCGC
> Ann Arbor MI 48109
> 734-647-5623
> 
> ______________________________________________
> R-devel@stat.math.ethz.ch mailing list
> https://www.stat.math.ethz.ch/mailman/listinfo/r-devel
> 
> 

-- 
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


[Rd] Segfault from knn.cv in class package (PR#6856)
Prof Brian Ripley