[datatable-help] Coercian to character

[Matthew Dowle]

It shouldn't coerce. What makes you think it does?

> DT = data.table(a=factor(c("a","b","b","c")),b=1:4)
> DT[,sum(b),by=a]
     a V1
[1,] a  1
[2,] b  5
[3,] c  4
> str(DT[,sum(b),by=a])
Classes ‘data.table’ and 'data.frame':	3 obs. of  2 variables:
 $ a : Factor w/ 3 levels "a","b","c": 1 2 3
 $ V1: int  1 5 4



On Thu, 2012-04-12 at 14:57 -0500, Damian Betebenner wrote:
> Data tablers
> 
>  
> 
> Does data.table now coerce factors to character variables when doing
> by summaries?
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> 
> If so, is there any way to not allow this coercion?
> 
>  
> 
> Thanks,
> 
>  
> 
> Damian Betebenner
> 
> Center for Assessment
> 
> PO Box 351
> 
> Dover, NH   03821-0351
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>  
> 
> Phone (office): (603) 516-7900
> 
> Phone (cell): (857) 234-2474
> 
> Fax: (603) 516-7910
> 
>  
> 
> dbetebenner at nciea.org
> 
> www.nciea.org
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