[R] ifelse problem - bug or operator error

[Jennifer Sabatier]

AAAAAHHHHHHH I GOT IT!!!!!!!!!!

And I *think* I understand about floating point arithmetic..

In this case vn$PM.DIST.TOT is the sum of proportions.  So, it should
be anywhere 0 and 1.

In our case, if it's anything other than 1 when vn$PM.EXP is greater
than 0  then it means something is wrong with one of the variables
used to sum vn$PM.DIST.TOT.

I was worried making it an integer will cause cases of 0.4 to be 0 and
look legal, when it's not (though it doesn't actually seem to be a
problem).

So, I just did what Michael and Peter suggested, after reading up on
floating points.

fpf <- 1e-05   # fpf = floating point fuzz

vn$PM.DIST_flag<-ifelse(vn$PM.EXP > 0 & abs(vn$PM.DIST.TOT - 1) > fpf , 1, 0)

YAAAAAYYYYY!!!!

Thanks, solved AND I learned something new.

Thanks, alll, and have a GREAT weekend!

Jen


On Fri, Aug 24, 2012 at 6:27 PM, Peter Ehlers <ehlers at ucalgary.ca> wrote:
> I see that you got other responses while I was composing an answer.
> Your 'example.csv' did come through for me, but I still can't
> replicate your PM.DIST_flag variable. Specifically, observations
> 30, 33, 36 and 40 are wrong.
>
> I agree with Rui, that there's something else going on. The data
> you've sent can't be the data that yielded the 'flag' variable
> or you didn't use the ifelse() function in the way that you've
> shown.
>
> I would start with a clean R session and I would use the 'convert
> logical to numeric' idea (or keep a logical rather than numeric
> flag):
>
>   vn <- transform(vn,
>           my_flag = ( (PM.EXP > 0) & (PM.DIST.TOT != 1) ) * 1 )
>
> It looks as though your PM.DIST.TOT variable is meant to be
> integer. If so, you might want to ensure that it is that type.
> Otherwise, you might want to use Michael's suggestion of using
> abs(... - 1) < 1e-05.
>
> Peter Ehlers
>
>
> On 2012-08-24 14:56, Jennifer Sabatier wrote:
>>
>> Hi Michael,
>>
>> Thanks for letting me know how to post data.  I will try to upload it
>> that way in a second.
>>
>> I can usually use code to make a reproducible dataset but this time
>> with the ifelse behaving strangely (perhaps, it's probably me) I
>> didn't think I could do it easily so I figured I would just put my
>> data up.
>>
>> I will check out the R FAQ you mentioned.
>>
>> Thanks, again,
>>
>> Jen
>>
>>
>>
>> On Fri, Aug 24, 2012 at 5:50 PM, R. Michael Weylandt
>> <michael.weylandt at gmail.com> wrote:
>>>
>>> On Fri, Aug 24, 2012 at 4:46 PM, Jennifer Sabatier
>>> <plessthanpointohfive at gmail.com> wrote:
>>>>
>>>> Hi Michael,
>>>>
>>>> No, I never use attach(), exactly for the reasons you state.  To do
>>>> due diligence I did a search of code for the function and it didn't
>>>> come up (I would have been shocked because I never us it!).
>>>>
>>>> Now that real data is up, does your suggestion still apply?  I am
>>>> reading it now.
>>>>
>>>
>>> If you mean the data you sent to Peter, it got scrubbed by the list
>>> servers as well (they are somewhat draconian, but appropriately so in
>>> the long run). The absolute best way to send R data via email (esp on
>>> this list) is to use the dput() function which will create a plain
>>> text representation of your data _exactly_ as R sees it. It's a little
>>> hard for the untrained eye to parse (I can usually get about 90% of
>>> what it all means but there's some stuff with rownames = NA I've never
>>> looked into) but it's perfectly reproducible to a different R session.
>>> Then us having the same data is a simple copy+paste away.
>>>
>>> For more on dput() and reproducibility generally, see
>>>
>>> http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example
>>>
>>> It could be the floating point thing (it's hard to say without knowing
>>> how your data was calculated), but Rui seems to think not.
>>>
>>> M
>>>
>>>> Thanks,
>>>>
>>>> Jen
>>>>
>>>> On Fri, Aug 24, 2012 at 5:38 PM, R. Michael Weylandt
>>>> <michael.weylandt at gmail.com> wrote:
>>>>>
>>>>> Off the wall / wild guess, do you use attach() frequently? Not
>>>>> entirely sure how it would come up, but it tends to make weird errors
>>>>> like this occur.
>>>>>
>>>>> M
>>>>>
>>>>> On Fri, Aug 24, 2012 at 4:36 PM, Jennifer Sabatier
>>>>> <plessthanpointohfive at gmail.com> wrote:
>>>>>>
>>>>>> Hi Rui,
>>>>>>
>>>>>> Thanks so much for responding but I think with my HTML problem the vn
>>>>>> data you made must not be the same.  I tried running your code on the
>>>>>> data (I uploaded a copy) and I got the same thing I had before.
>>>>>>
>>>>>> Jen
>>>>>>
>>>>>> On Fri, Aug 24, 2012 at 5:28 PM, Rui Barradas <ruipbarradas at sapo.pt>
>>>>>> wrote:
>>>>>>>
>>>>>>>
>>>>>>> 165114 1 0  0 0 0  417313 1 0  3546 1 0  4613 1 0  225460 1 0  6417 1
>>>>>>> 1  23
>>
>>
>> ______________________________________________
>> 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.
>>
>