[R] For is.numeric condition in user input

[jim holtman]

You probably want something like this:

mesg <- 'input: '
repeat{
   value <- suppressWarnings(as.numeric(readline(mesg)))
   if (!is.na(value)) break
   mesg <- "try again: "
}


On Mon, Jul 25, 2011 at 8:27 AM, Bansal, Vikas <vikas.bansal at kcl.ac.uk> wrote:
> I have tried this,and it is working.But the thing is if user will input a character rather than number,in the end it is showing a warning message-
>
> Warning messages:
> 1: NAs introduced by coercion
>
> and this is not good for my tool as I do not want to show this warning to the user.
>
>
>
> Typo on my part; should be 'is.na':
>
> so you would do:
>
> repeat{
>    value <- as.numeric(readline())
>    if (!is.na(value)) break
> }
>
> On Mon, Jul 25, 2011 at 8:05 AM, Bansal, Vikas <vikas.bansal at kcl.ac.uk> wrote:
>> Thanks for your reply.But I have never seen ia.na in R.Can you please tell me how to use this?
>> So you are saying rather than is.numeric,I have to test user input by ia.na?
>>
>>
>> Thanking you,
>> Warm Regards
>> Vikas Bansal
>> Msc Bioinformatics
>> Kings College London
>> ________________________________________
>> From: jim holtman [jholtman at gmail.com]
>> Sent: Monday, July 25, 2011 12:58 PM
>> To: Bansal, Vikas
>> Cc: Smart Guy; Ista Zahn; r-help at r-project.org
>> Subject: Re: [R] For is.numeric condition in user input
>>
>> If you run a simple test (that is what is nice about R being
>> interpreted), you will see that 'as.numeric' is TRUE; what you want to
>> test for is 'ia.na':
>>
>>> a
>> [1] "12as"
>>> as.numeric(a)
>> [1] NA
>> Warning message:
>> NAs introduced by coercion
>>> is.numeric(as.numeric(a))
>> [1] TRUE
>> Warning message:
>> NAs introduced by coercion
>>
>>
>>
>> On Mon, Jul 25, 2011 at 7:49 AM, Bansal, Vikas <vikas.bansal at kcl.ac.uk> wrote:
>>> Thanks for your reply.I know readline will give me a character.But if I will do something like this-
>>>
>>>
>>>> readnumber<- function()
>>>>  {
>>>> for(j in 1:10){
>>>>  value=readline("enter the threshold for number of reads: ")
>>>> value=as.numeric(value)
>>>>  if(is.numeric(value)==T)
>>>> {return(value)
>>>> break}
>>>> else
>>>> print("wrong number Please enter numerical value ")}
>>>>
>>>>  }
>>>
>>> if i will change value as numeric and if now user will input a character like a or b rather than a number like 4 or 5 or 6,then my code is not showing message-
>>> wrong number Please enter numerical value
>>>
>>> That is why I am confused now-I have tried with- value=as.numeric(value)
>>> and without this also.But did not find any solution.
>>>
>>>
>>> Thanking you,
>>> Warm Regards
>>> Vikas Bansal
>>> Msc Bioinformatics
>>> Kings College London
>>> ________________________________________
>>> From: Smart Guy [smartguy3k at gmail.com]
>>> Sent: Monday, July 25, 2011 6:39 AM
>>> To: Ista Zahn
>>> Cc: Bansal, Vikas; r-help at r-project.org
>>> Subject: Re: [R] For is.numeric condition in user input
>>>
>>> Yes, thats right, readline will give you character and now you need to convert it to numeric to make it work.
>>>
>>> Thanks
>>> SmartG
>>>
>>> On 25 July 2011 08:51, Ista Zahn <izahn at psych.rochester.edu<mailto:izahn at psych.rochester.edu>> wrote:
>>> readline always returns a character. See ?readline for details.
>>>
>>> Best,
>>> Ista
>>>
>>> On Sun, Jul 24, 2011 at 10:59 PM, Bansal, Vikas <vikas.bansal at kcl.ac.uk<mailto:vikas.bansal at kcl.ac.uk>> wrote:
>>>> Dear all,
>>>>
>>>> I am using the following function so that user can input a numerical value.
>>>>
>>>> readnumber<- function()
>>>>  {
>>>> for(j in 1:10){
>>>>  value=readline("enter the threshold for number of reads: ")
>>>>  if(is.numeric(value)==T)
>>>> {return(value)
>>>> break}
>>>> else
>>>> print("wrong number Please enter numerical value ")}
>>>>
>>>>  }
>>>>
>>>> But if by chance user tries to put character it will show the message-
>>>>  wrong number Please enter numerical value
>>>>
>>>> now when I am calling this function and entering numerical value,then also it is showing the message-wrong number Please enter numerical value
>>>>
>>>> Can you please tell me what mistake I am doing?
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Thanking you,
>>>> Warm Regards
>>>> Vikas Bansal
>>>> Msc Bioinformatics
>>>> Kings College London
>>>> ______________________________________________
>>>> R-help at r-project.org<mailto:R-help at r-project.org> mailing list
>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>>>> and provide commented, minimal, self-contained, reproducible code.
>>>>
>>>
>>>
>>>
>>> --
>>> Ista Zahn
>>> Graduate student
>>> University of Rochester
>>> Department of Clinical and Social Psychology
>>> http://yourpsyche.org
>>>
>>> ______________________________________________
>>> R-help at r-project.org<mailto:R-help at r-project.org> mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>>
>>>
>>> --
>>> SmartG
>>>
>>> ______________________________________________
>>> R-help at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>
>>
>>
>> --
>> Jim Holtman
>> Data Munger Guru
>>
>> What is the problem that you are trying to solve?
>>
>
>
>
> --
> Jim Holtman
> Data Munger Guru
>
> What is the problem that you are trying to solve?
>



-- 
Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?