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Problem with scoping a variable value

5 messages · Tolga Uzuner, Gabor Grothendieck, Paul Roebuck +1 more

Tolga Uzuner
# 
Hi there,

I have a function which has a variable called show as an input:

richardson.grad <- function(func, x, d=0.01, eps=1e-4, r=6, show=F){
# do some things
   if(show) {

        cat("\n","first order approximations", "\n")       
        print(a.mtr, 12)


    }
#do more things and return
}

The show variable is being used as a flag to show intermediate results.

Interestingly enough, I have downloaded a package recently which defines 
the show variable as a function:

 > show
standardGeneric for "show" defined from package "methods"

function (object)
standardGeneric("show")
<environment: 01676F7C>
Methods may be defined for arguments: object

 >

Now, all of a sudden, the function I had defined earlier is scoping up 
to this new value, and is thus not working:

 > richardson.grad(function(x) x^2,2)
Error in if (show) { : argument is not interpretable as logical
 >

I could always redefine show in richardson.grad to be something else but 
something seems wrong: why is richardson.grad not looking up show's 
value in the  function ? How would I fix this ?

Thanks in advance,
Tolga
Gabor Grothendieck
# 
Without a reproducible example one can only guess but
perhaps the problem is not show but that you have a variable
F.  Try writing out F as FALSE.
On 2/16/06, Tolga Uzuner <tolga at coubros.com> wrote:
Paul Roebuck
#
On Thu, 16 Feb 2006, Tolga Uzuner wrote:

            

      
      
      
    

        
You didn't spell out the logical value 'FALSE' which may
be causing your problem. Consider this alternative also...

richardson.grad <- function(func,
                            x,
                            d = 0.01,
                            eps = 1e-4,
                            r = 6,
                            verbose = getOption("verbose")) {
    ## do some things
    if (verbose) {
         cat("\n", "first order approximations:", "\n")
         print(a.mtr, 12)
    }
    ## do more things and return
}

----------------------------------------------------------
SIGSIG -- signature too long (core dumped)

  
  


  


      

    

    

      
      

        


  

        

      Tolga Uzuner
    

    

      
      #
    

  


  

      
You are a star... that was it. Many thanks,
Tolga

-----Original Message-----
From: Gabor Grothendieck [mailto:ggrothendieck at gmail.com] 
Sent: 16 February 2006 20:24
To: Tolga Uzuner
Cc: r-help at stat.math.ethz.ch
Subject: Re: [R] Problem with scoping a variable value

Without a reproducible example one can only guess but
perhaps the problem is not show but that you have a variable
F.  Try writing out F as FALSE.

        
On 2/16/06, Tolga Uzuner <tolga at coubros.com> wrote:

            

      
      
      
    

        

      
      
    

        
http://www.R-project.org/posting-guide.html

            

      
      
      
    

  
  


  


      

    

    

      
      

        


  

        

      Philippe GROSJEAN
    

    

      
      #
    

  


  

      
Paul Roebuck wrote:

            

      
      
      
    

        
This is definitely the best solution, and Paul is right: you have to use 
  FALSE in preference to F (FALSE is a reserved word, F is not in R).

Now, you should know that show() *is* a generic function (it is the 
default method for S4 objects), and it is a very bad idea to use it as 
named argument for functions. I would suggest to use Paul's suggestion 
instead, or to change it as 'show.it = FALSE', as a minimum.
Best,

Philippe Grosjean