[R] a very simple question

[Berend Hasselman]

On 19-03-2012, at 13:47, Dajiang Liu wrote:

> 
> Thanks a lot for the clarification. I just find it very bizarre that if you run a=0.1*(1:9);which(a==0.4) 
> it returns the right answer. Anyway, I will pay attention next time. Thanks a lot. 
> 


Look at

> a = 0.1*(1:4)
>  a - 0.4
[1] -0.3 -0.2 -0.1  0.0
> 


Berend

>> Date: Mon, 19 Mar 2012 08:59:59 +0100
>> From: Rainer.Schuermann at gmx.net
>> Subject: Re: [R] a very simple question
>> To: ldjstudy at hotmail.com; r-help at r-project.org
>> 
>> As to the reasons, David as given you the necessary hints.
>> 
>> In order to get around the issue, here is what I do:
>> 
>>> a <- round( 0.1 * ( 1:9 ), 1 )
>>> a
>> [1] 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
>>> which( a == 0.3 )
>> [1] 3
>> 
>> Rgds,
>> Rainer
>> 
>> 
>> -------- Original-Nachricht --------
>>> Datum: Sun, 18 Mar 2012 21:43:54 +0000
>>> Von: Dajiang Liu <ldjstudy at hotmail.com>
>>> An: r-help at r-project.org
>>> Betreff: [R] a very simple question
>> 
>>> 
>>> Dear All,
>>> I have a seemingly very simple question, but I just cannot figure out the
>>> answer. I attempted to run the following:a=0.1*(1:9);which(a==0.3);it
>>> returns integer(0). But obviously, the third element of a is equal to 0.3. 
>>> I must have missed something. Can someone kindly explain why? Thanks a
>>> lot.
>>> Regards,Dajiang
>>> 		 	   		  
>>> 	[[alternative HTML version deleted]]
>>> 
>>> ______________________________________________
>>> 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.
>> 
>> -- 
>> -------
>> 
>> Gentoo Linux with KDE
>> 
> 		 	   		  
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> 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.