[datatable-help] Writing a good "WHERE" statement

[John Kerpel]

Thx Eduard - it's about 5% faster your way according to rbenchmark.  Hey,
latency is latency....just got a need for speed...

Best,

John


On Wed, Aug 14, 2013 at 9:58 AM, Eduard Antonyan
<eduard.antonyan at gmail.com>wrote:

> you could use Days %in% c(1,5,10,20,30,60,90) instead, or iff Days is the
> first key J(c(1,5,10,20,30,60,90))
>
>
> On Wed, Aug 14, 2013 at 9:30 AM, John Kerpel <john.kerpel2 at gmail.com>wrote:
>
>> Folks:
>>
>> I've been working more and more in data.table and it gets better and
>> better as I learn to use it....
>>
>> So my question is, in the following example, is the Where statement
>> inefficient because I'm using "==" ?  (I just want to use the subsets where
>> days are equal to the values in the statement)
>>
>> Should I do this another way? (Btw, I get exactly the right answer using
>> this approach...)
>>
>> db <- DB4[
>>
>>   Days==1 | Days==5 | Days==10 | Days==20 | Days==30 | Days==60 |
>> Days==90,
>>
>>   j =   {list(v=m_func(x,y,z))},
>>
>>   by= "Date,Indicator,Days"
>>
>>   ]
>>
>> If more detail is necessary, lmk. Date, Indicator, and Days are keys.
>>
>> Best,
>>
>> John
>>
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>>
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>>
>
>
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