[R] question on maximum of each row of the matrix

[David Winsemius]

On Mar 5, 2010, at 7:30 AM, khazaei at ceremade.dauphine.fr wrote:

> Hi,
> I  used the  apply()function  to compute the maximum of the each row  
> of
> the matrix, but in my application sometime the matrix  has just one  
> row,
> and the apply() dosen't work.
> Could you please give me some hints?

If your matrix became a one row entity as a result of an indexing or  
subsetting operation, then you could prevent the loss of its matrix  
classification by using the drop=FALSE argument.

 > strt <- matrix(1:8, ncol=2)
 > strt[ , 2, drop=FALSE]
      [,1]
[1,]    5
[2,]    6
[3,]    7
[4,]    8
 > apply(strt[ , 2, drop=FALSE], 1, max)
[1] 5 6 7 8


>
> thank you
> khazaei
-- 
David Winsemius, MD
Heritage Laboratories
West Hartford, CT