[R] read-in, error???

[Sarah Goslee]

Hi Istvan,

That's most unusual, and quite unlikely (and much larger than the
usual floating-point rounding errors).

Please provide a reproducible example. I assume you got the data from here:
http://www.itl.nist.gov/div898/strd/anova/SmLs07.dat

What did you do with it then? How did you delete the header rows?

What R code did you use to read it in?

What OS and version of R are you working with?

R has been well-validated; it's more likely that you did something
sub-optimal while importing the data.

Sarah

On Fri, May 4, 2012 at 9:54 AM, Istvan Nemeth <furgeurge at gmail.com> wrote:
> Dear Users!
>
> I encountered with some problem in data reading while I challenged R (and
> me too) in a validation point of view.
> In this issue, I tried to utilize some reference datasets (
> http://www.itl.nist.gov/div898/strd/index.html).
> And the result departed a bit from my expectations. This dataset dedicated
> to challenge cancellation and accumulation errors (case SmLs07), that's why
> this uncommon look of txt file.
>
> Treatment   Response
>           1    1000000000000.4
>           1    1000000000000.3
>           1    1000000000000.5
>           ......
>           2    1000000000000.2
>           2    1000000000000.4
>           .....
>           3    1000000000000.4
>           3    1000000000000.6
>           3    1000000000000.4
>           .........
> then after a read.table() I expect the same set instead I've got this:
>
>    Treatment              Response
> 1           1 1000000000000.4000244
> 2           1 1000000000000.3000488
> 3           1 1000000000000.5000000
> .........
> 22          2 1000000000000.3000488
> 23          2 1000000000000.1999512
> 24          2 1000000000000.4000244
> .......
> 58          3 1000000000000.4000244
> 59          3 1000000000000.5999756
> 60          3 1000000000000.4000244
> 61          3 1000000000000.5999756
> 62          3 1000000000000.4000244
> ......
> a lots of number from the space. I assume that these numbers come from the
> binary representation of such a tricky decimal numbers but my question is
> how can I avoid this feature of the binary representation?
>
> Moreover, I wondered that it may raise some question in a regulated
> environment.
>

-- 
Sarah Goslee
http://www.functionaldiversity.org