R help - Mar 2010 - question on maximum of each row of the matrix

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?

thank you
khazaei

Hi:

Turn it into a matrix:
> x <- 1:10
> x <- matrix(x, nrow = 1)
> class(x)
[1] "matrix"
> apply(x, 1, max)
[1] 10

HTH,
Dennis

On Fri, Mar 5, 2010 at 4:30 AM, <khazaei@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?
>
> thank you
> khazaei
>
> ______________________________________________
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> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
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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