See code below. When two data tables are merged (by their key variable(s)),
that key disappears in the resulting table. While this is probably not strictly
a bug, it would seem that the user would most likely want to preserve the key
in the output (especially if just enlarging the original data table, e.g.
dt2<-merge(dt1,dt2).)
> dt1<-data.table(a=1:6,b=11:16,key="a")
> dt2<-data.table(a=1:6,c=21:26,key="a")
> dt3<-merge(dt1,dt2)
>
>
NAME NROW MB COLS KEY
[1,] dt1 6 1 a,b a
[2,] dt2 6 1 a,c a
[3,] dt3 6 1 a,b,c
Total: 3MB
Joseph G. Voelkel, Ph.D.
Professor, Center for Quality and Applied Statistics
Kate Gleason College of Engineering
Rochester Institute of Technology
V 585-475-2231
F 585-475-5959
[email protected]
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