On Tue, May 20, 2014 at 8:45 PM, Nathaniel Graham <[email protected]> wrote:
> Thanks! That's a good idea, and a lot simpler than what I was concocting in
> my head. I'll give that a try. I think--just for for posterity--you mean
>
> DT[, importance := 0 - is.na(V3)]
>
> rather than 0 + is.na(V3), so that rows with V3 are lower than rows without.
0 + is.na(V3) was intended. We want the good rows to have a lower
importance than the bad rows so 0+is.na(V3) gives a non-NA V3 an
importance of 0 and it gives a V3 which is NA an importance of 1.
When we sort them using setkey the non-NA of 0 comes first so it is
the one picked by unique.
> DT[, importance := 0+is.na(V3)]
> setkey(DT, V1, V2, importance)
> unique(DT, by = c("V1", "V2"))
V1 V2 V3 importance
1: 1 3 TRUE 0
2: 1 4 TRUE 0
3: 2 3 TRUE 0
4: 2 4 TRUE 0
5: 3 1 NA 1
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