[datatable-help] rbindlist and unique

[Nathaniel Graham]

My mistake, you're correct.  I reversed it in my head.

-------
Nathaniel Graham
npgraham1 at gmail.com
npgraham1 at uky.edu
https://sites.google.com/site/npgraham1/


On Tue, May 20, 2014 at 8:50 PM, Gabor Grothendieck <ggrothendieck at gmail.com
> wrote:

> On Tue, May 20, 2014 at 8:45 PM, Nathaniel Graham <npgraham1 at gmail.com>
> 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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