[R] wrong name of input file and goto like function

[MacQueen, Don]

While you study the documentation as others suggested, may I suggest that you take a look at the
  file.exists()
function. Here is an example of using file.exists().

tmpfile <- define()

if (file.exists(tmpfile)) {
  ## read the file
} else {
  ## tell the user to try again
}

On Jul 24, 2011, at 7:05 AM, Bansal, Vikas wrote:

> Dear all,
> 
> I have a question and need your help please.
> I have the following code which is asking user to enter the name of their file.
> 
> define<- function() 
> { 
> readline("enter the name of your file: ") 
> } 
> 
> df=read.table(define(),fill=T,sep="\t",colClasses = "character")
> 
> Now I want if user will input wrong name of file the code should not end and it should show a message-
> 
> if()
> {
> print("wrong name of the file Please enter again ")
> 
> }
> 
> now I want to ask what should be the condition of if so that if user will input wrong file name it will show this message and then i want to use something like goto so that it should again start with the code which is before if condition-
> 
> df=read.table(define(),fill=T,sep="\t",colClasses = "character")
> 
> 
> 
> 
> so the code should be-
> 
> define<- function(x) 
> { 
> readline("enter the name of your file: ") 
> } 
> 
> df=read.table(define(),fill=T,sep="\t",colClasses = "character")           ##starline
> 
> 
> if(## some condition here)
> {
> print("wrong name of the file Please enter again ")
> ## some goto function so that it should goto (starline)
> }
> 
> 
> 
> 
> 
> 
> 
> Thanking you,
> Warm Regards
> Vikas Bansal
> Msc Bioinformatics
> Kings College London
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--------------------------------------------------------
Don MacQueen
Lawrence Livermore National Laboratory
(925) 423-1062
macqueen1 at llnl.gov