R help - Dec 2004 - list(0) to integer

Hello
I've another question :-)
I would like to transform a list to a integer.
I must be sure that the number entered by the user is
an integer! Thus, I've made :


repeat{
  cat("Effectif des populations (integer):")
  n<-scan("",n=1,what=list(0),quiet=TRUE)

  if (is.integer(n[[1]])==TRUE) break
  print("L'effectif des population doit etre un
entier")
  }

That doesn't work of course but I've no idea to do
this. How verify that n[[1]] is an integer an
transform them as an integer (as.integer(n) doesn't
work!) Someone can help me? Thanks!
Fred

On Mon, 27 Dec 2004 03:18:53 -0800 (PST)
Frederic renaud <fren2 at yahoo.com> wrote:
> Hello
> I've another question :-)
> I would like to transform a list to a integer.
> I must be sure that the number entered by the user is
> an integer! Thus, I've made :
> 
> 
> repeat{
>   cat("Effectif des populations (integer):")
>   n<-scan("",n=1,what=list(0),quiet=TRUE)
> 
>   if (is.integer(n[[1]])==TRUE) break
>   print("L'effectif des population doit etre un
> entier")
>   }
if (!is.integer(unlist(n))) stop("L'effectif ...")

You don't need `== TRUE' (and I guess you meant `== FALSE')
An error action can be executed using stop("some error message").
`break' breaks out of the loop (ie goes to the first statement
after the loop), so the print statement cannot be executed.

Are you sure you need n to be a list ?

HTH,
Tobias
>  That doesn't work of course but I've no idea to do
> this. How verify that n[[1]] is an integer an
> transform them as an integer (as.integer(n) doesn't
> work!) 
> Someone can help me? Thanks!
> Fred
> 
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Re-Hello frederic,

Don't worry, i have the same english speaking problem, here is what i 
suggest :

n <- natScan()

natScan <- function(){
 
cat("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n")
  cat("Give me a natural (everything after the '.' will be
ignored)\n")
  n <- scan("", character(), 1,quiet=T)
  n  <- as.integer(n)
  if(length(n)==0||is.na(n)){
     cat("!! that's not what i want !!\n")
     return(natScan())
  }
  return(n)
}

Hope this helps


Frederic renaud a ??crit :
>Because if the user write something else (a real or a
>character), the program stop. I want in this case (if
>the user don't write a natural) that the program write
>again :" A natural, please!"
>I've some difficult to speak english! Do you
>understand?
>Thanks
>Fred
>
>
>--- Romain Fran??ois <francoisromain at free.fr> wrote:
>
>  
>
>>Hello frederic,
>>
>>why don't you just try something like :
>>
>>n <- scan("", integer(), 1)
>>
>>
>>You may also need to take a look there : 
>>http://zoonek2.free.fr/UNIX/48_R/all.html
>>and maybe there http://addictedtor.free.fr (for the
>>moment there is 
>>noting usefull there but soon ....)
>>
>>
>>Frederic renaud a ??crit :
>>
>>    
>>
>>>Hello
>>>I've another question :-)
>>>I would like to transform a list to a integer.
>>>I must be sure that the number entered by the user
>>>      
>>>
>>is
>>    
>>
>>>an integer! Thus, I've made :
>>>
>>>
>>>repeat{
>>> cat("Effectif des populations (integer):")
>>> n<-scan("",n=1,what=list(0),quiet=TRUE)
>>>
>>> if (is.integer(n[[1]])==TRUE) break
>>> print("L'effectif des population doit etre un
>>>entier")
>>> }
>>>
>>>That doesn't work of course but I've no idea to do
>>>this. How verify that n[[1]] is an integer an
>>>transform them as an integer (as.integer(n) doesn't
>>>work!) Someone can help me? Thanks!
>>>Fred
>>>
>>>_
>>>      
>>>
-- 
Romain FRANCOIS : francoisromain at free.fr
page web : http://addictedtor.free.fr/  (en construction)
06 18 39 14 69 / 01 46 80 65 60
_______________________________________________________
Etudiant en 3eme ann??e
Institut de Statistique de l'Universit?? de Paris (ISUP)
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http://www.isup.cicrp.jussieu.fr/