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

[Christofer Bogaso]

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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