[R] Is there a bug in kmeans in package mva?

Prof Brian D Ripley ripley at stats.ox.ac.uk
Tue Jul 25 14:55:10 CEST 2000


On Tue, 25 Jul 2000, Art Salwin wrote:

> I created a numeric vector of 49 elements and call kmeans as
> follows:

The help page says

       x: A data frame or matrix of data. 

so that is your error.

> kmeans(x,3)
> The second argument, number of centers, is allowed to be a
> constant per
> the documentation.  However, the call doesn't work and
> generates the
> following error message:
> Error in ncol(x) != ncol(centers) : comparison (2) is
> possible only for vector types

right, ncol(x) is NULL.

> Is this a bug or am I doing something wrong?
> 
> Looking at the code within kmeans, it appears the statement 
> if(ncol(x)!=ncol(centers))
> is where it fails, since centers does not get coerced to be
> a matrix
> and ncol(centers) is NULL.
> -- 
> Art Salwin
> salwin at mitretek.org
> (202) 863-2985
> (202) 863-2988 (fax)
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-- 
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 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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