[R] Error:length of dimnames [2] not equal to array extent ?

[Prof Brian Ripley]

Please use the debugging facilities to investigate further -- you 
have not even shown the traceback, let alone used dump.frames and the 
debugger.

On Fri, 2 Jul 2004, Robin Gruna wrote:

> Hi everyone,
> I have the following problem:
> I want to perform a LDA with the function lda().
> My data object mat.data is a matrix with dimensions
> 
> > dim(mat.data)
> [1] 1228   44
> 
> and my grouping vector grp has length 1228:
> 
> > length(grp)
> [1] 1228
> 
> Every time I call lda(), the following error message occurs:
> 
> > lda(mat.data,grp)
> Error in lda.default(x, grouping, ...) : length of dimnames [2] not equal to
> array extent

dimnames [2] are the column names.  That's an error in dimnames<-.

> In order to find the error I created a matrix mat.test
> 
> mat.test<-matrix(1:500,nrow=1228,ncol=44)
> 
> with arbitrary entries an the same attributes as mat.data:
> 
> > dimnames(mat.test)
> NULL
> 
> > dimnames(mat.data)
> NULL
> 
> But with the test object mat.test there occurs no error !
> Can somebody help me, this really makes me crazy,
> thanks,

Learning to debug R will alleviate the symptoms.

-- 
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