[datatable-help] Subsetting Bug?

[Michael Smith]

Thanks, Øyvind, and yes, the same names are intentional. I guess it has
something to do with the scope in which the variable gets evaluated, and
that's why I have brackets around the CIK to refer to the "outer" CIK.
Nonetheless, I was expecting the same results in both calls.


On 11/07/2014 05:07 PM, Øyvind wrote:
> Hi
> I'm not sure if this was intentional and maybe not what you're asking,
> but the problem is caused by the string CIK being called the same as the
> variable CIK. Somehow in the first example "CIK" is understood as the
> string and in the second as the variable. Thus in the second example
> you're asking if the variable CIK == the variable CIK. If you change CIK
> to CIK2 everything works as expected:
> 
> CIK2 = "0000839087"
> DT[CIK == (CIK2)][FileDate <= 10104]
> 
>           CIK FileDate
> 1: 0000839087    10081
> 
> DT[CIK == (CIK2)&FileDate <= 10104]
> 
>           CIK FileDate
> 1: 0000839087    10081
> 
> I guess someone else has to explain why data.table understands CIK and
> CIK differently.
> 
> 
> Øyvind
> 
> On Fri, Nov 7, 2014 at 9:51 AM, Michael Smith <my.r.help at gmail.com
> <mailto:my.r.help at gmail.com>> wrote:
> 
>     Shouldn't the last two commands below yield identical results?
> 
>     DT <-
>         data.table(
>             CIK = c("0000060512", "0000839087"),
>             FileDate = c(8680, 10081))
>     CIK = "0000839087"
>     DT[CIK == (CIK)][FileDate <= 10104]
> 
>               CIK FileDate
>     1: 0000839087    10081
> 
>     DT[CIK == (CIK) & FileDate <= 10104]
> 
>               CIK FileDate
>     1: 0000060512     8680
>     2: 0000839087    10081
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