R help - May 2003 - error-prone feature?

Hi All,

  while looking why the cclust(cclust) doesn't work for 1-dimensional data,
  I've found unpleasant behavior in semantics of R. Indeed:

    is.matrix(matrix(cbind(c(1,2,3,4)),ncol=2)[1:2,])  == TRUE

  but:

    is.matrix(matrix(c(1,2))[1:2,]) == FALSE
  

kind regards,
Valery A.Khamenya
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Bioinformatics Department
BioVisioN AG, Hannover

Well, that is in all good texts on R, together with the 
solution: drop=FALSE.  See ?"[" for the on-line details.

`S Programming' says

  S programmers have often overlooked these rules, which can result
  in puzzling or incorrect behaviour when just one observation or
  variable meets some selection criterion.

I suggest you get yourself a copy and read it.


On Thu, 15 May 2003, Khamenia, Valery wrote:
>   while looking why the cclust(cclust) doesn't work for 1-dimensional
data,
>   I've found unpleasant behavior in semantics of R. Indeed:
> 
>     is.matrix(matrix(cbind(c(1,2,3,4)),ncol=2)[1:2,])  == TRUE
> 
>   but:
> 
>     is.matrix(matrix(c(1,2))[1:2,]) == FALSE

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
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