[R] For is.numeric condition in user input

[jim holtman]

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?