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

[John Kerpel]

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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