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Newbie help on dim

9 messages · Christian Prinoth, Dimitris Rizopoulos, Andy Bunn +3 more

Original
Christian Prinoth
# 
Hi, if I do

Z<-rnorm(50)
Followed by
Dim(Z)
I get NULL. Is this correct? Shouldn't I get 50 instead?

TIA
Chris

DISCLAIMER:\ L'utilizzo non autorizzato del presente messagg...{{dropped}}
Dimitris Rizopoulos
# 
yes it is correct! look at ?dim() for more info. In this case you need 
length(), i.e.,

Z <- rnorm(50)
length(Z)


I hope it helps.

Best,
Dimitris

----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/16/336899
Fax: +32/16/337015
Web: http://www.med.kuleuven.be/biostat/
     http://www.student.kuleuven.be/~m0390867/dimitris.htm



----- Original Message ----- 
From: "Christian Prinoth" <Christian.Prinoth at epsilonsgr.it>
To: <r-help at stat.math.ethz.ch>
Sent: Thursday, September 01, 2005 2:00 PM
Subject: [R] Newbie help on dim
Andy Bunn
# 
Check out the "dim vs length for vectors" thread:

http://finzi.psych.upenn.edu/R/Rhelp02a/archive/50720.html

This thread goes through the bug-or-feature discussion which is always
entertaining from a socio-R perspective.

Also, note "Dim" with a capital D doesn't exist.

HTH, Andy
Uwe Ligges
#
Christian Prinoth wrote:

            

      
      
      
    

        
No, because Z has no dim attribute. ?dim tells you:

"For an array (and hence in particular, for a matrix) dim retrieves the 
dim attribute of the object. It is NULL or a vector of mode integer."

            

      
      
      
    

        

      
      
    

        
Yes, PLEASE do read the posting guide! 
http://www.R-project.org/posting-guide.html


Uwe Ligges

  
  


  


      

    

    

      
      

        


  

        

      Chuck Cleland
    

    

      
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Should the Value: section of the help page read:

For an array (and hence in particular, for a matrix) dim retrieves the
dim attribute of the object. It is NULL for a vector of mode integer.

NOTE: for not or in the second sentence.

        
Uwe Ligges wrote:

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

      
      
    

        

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      Uwe Ligges
    

    

      
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Chuck Cleland wrote:

        

            

      
      
      
    

        
NO!!! The help page is correct!

The *value* is either NULL *or* a vector of mode integer.
It is always NULL for any vector without dim attribute (also for 
character vectors!):

  x <- "a"
  dim(x) # NULL
  dim(x) <- 1
  dim(x) # 1

Uwe Ligges

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

      
      
    

            

      
      
      
    

  
  


  


      

    

    

      
      

        


  

        

      Achim Zeileis
    

    

      
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On Thu, 01 Sep 2005 08:25:14 -0400 Chuck Cleland wrote:

        

            

      
      
      
    

        
This statement is true, but less general than
  It is NULL or a vector of mode integer.
hence the latter is surely preferred.
Z

            

      
      
      
    

        

      
      
    

        

      
      
    

            

      
      
      
    

        

      
      
    

  
  


  


      

    

    

      
      

        


  

        

      Uwe Ligges
    

    

      
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Achim Zeileis wrote:

        

            

      
      
      
    

        
Z, in fact, it is not true:

  x <- integer(1)
  dim(x) <- 1
  typeof(x) # "integer"
  dim(x)    # 1

Best,
Uwe

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

      
      
    

  
  


  


      

    

    

      
      

        


  

        

      Achim Zeileis
    

    

      
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On Thu, 01 Sep 2005 14:44:53 +0200 Uwe Ligges wrote:

        

            

      
      
      
    

        
But then:
  is.vector(x) # FALSE
but let's not start nitpicking here.
Z