[datatable-help] 'OR' operation with data.table

[Arunkumar Srinivasan]

How about this? 
DT[CJ(c("a", "b"), c("B", "D"))]

Arun


On Saturday, November 16, 2013 at 11:53 PM, Christofer Bogaso wrote:

> Hello all,
> 
> I am a new user of data.table and really started to liking it :)
> 
> I am seeking some suggestion on how I can implement 'OR'/AND' operator to fetch a subset of a data.table. 
> 
> Below is my example data.table (my actual data.table is quite big):
> 
> DT = data.table(x = 1:20, y1 = rep(letters[1:4], 5), y2 = rep(LETTERS[1:4], each = 5))
> setkey(DT, y1, y2)
> 
> 
> > DT
>      x y1 y2
>  1:  1  a  A
>  2:  5  a  A
>  3:  9  a  B
>  4: 13  a  C
>  5: 17  a  D
>  6:  2  b  A
>  7:  6  b  B
>  8: 10  b  B
>  9: 14  b  C
> 10: 18  b  D
> 11:  3  c  A
> 12:  7  c  B
> 13: 11  c  C
> 14: 15  c  C
> 15: 19  c  D
> 16:  4  d  A
> 17:  8  d  B
> 18: 12  d  C
> 19: 16  d  D
> 20: 20  d  D
> 
> 
> 
> Now I want to fetch those rows for which "y1 = a OR b  AND y2 = B OR D"
> 
> with ordinary data.frame, this is straightforward to achieve, however I am wondering what could be the data.table way for fast computation. 
> 
> I would really appreciate for your help/pointer.
> 
> Thanks and regards,
> 
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