[R] Significant digits for checking values of variable?

[David Afshartous]

Thanks.  Is there simple way around this for simple checking of single
values?  The all.equal() mentioned in the FAQ doesn't seem appropriate.

 X = c(1.2, 2)
> X.new = X -1
> X == 1.2
[1]  TRUE FALSE
> X.new == .2
[1] FALSE FALSE



On 8/27/08 11:47 AM, "jim holtman" <jholtman at gmail.com> wrote:

> FAQ 7.31
> 
> On Wed, Aug 27, 2008 at 11:51 AM, David Afshartous
> <dafshartous at med.miami.edu> wrote:
>> 
>> All,
>> 
>> I'm witnessing some strange behavior when checking the values of one of my
>> variables.  My guess is that it has something to do with the number of
>> significant digits being represented, but perhaps not as my variable was
>> created from other variables that only had one decimal place.  See below.
>> I'm sure this is something basic, any suggestions much appreciated.
>> 
>> Cheers,
>> David
>> 
>> 
>>> visit.2.SEK.delta.baseline
>>  [1]  0.1 -0.7  0.8 -0.1 -0.5  0.8  0.7  0.2  0.4  0.3  0.6  0.6  0.3  0.8
>> 0.8  0.3  0.4  0.8
>>> visit.2.SEK.delta.baseline > 0
>>  [1]  TRUE FALSE  TRUE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
>> TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
>>> visit.2.SEK.delta.baseline ==  .8
>>  [1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
>> FALSE FALSE FALSE FALSE FALSE FALSE
>> ### but some of the values are equal to .8
>> 
>> ## here it is okay when I try to reproduce
>>>  junk = c(0.1, -0.7,0.8, -0.1, -0.5,  0.8,  0.7,  0.2,  0.4,  0.3,  0.6,
>>> 0.6,
>> 0.3,  0.8,  0.8,  0.3,  0.4,  0.8 )
>>> junk == .8
>>  [1] FALSE FALSE  TRUE FALSE FALSE  TRUE FALSE FALSE FALSE FALSE FALSE FALSE
>> FALSE  TRUE  TRUE FALSE FALSE  TRUE
>> 
>> ______________________________________________
>> 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.
>> 
> 
>