I am trying to use a data table as a lookup table:
> (dt <- data.table(myid=rep(11:12,3),zz=1:6,key=c("myid","zz")))
myid zz
1: 11 1
2: 11 3
3: 11 5
4: 12 2
5: 12 4
6: 12 6
> (id2name <- data.table(id=11:14,name=letters[1:4],key="id"))
id name
1: 11 a
2: 12 b
3: 13 c
4: 14 d
What I want is
> (res <- data.table(myid=rep(11:12,3),zz=1:6,name=rep(letters[1:2],3),key=c("myid","zz")))
myid zz name
1: 11 1 a
2: 11 3 a
3: 11 5 a
4: 12 2 b
5: 12 4 b
6: 12 6 b
however, the join I tried failed:
> dt[id2name]
Starting binary search ...done in 0 secs
Error in vecseq(f__, len__, if (allow.cartesian) NULL else as.integer(max(nrow(x), :
Join results in 8 rows; more than 6 = max(nrow(x),nrow(i)). Check for duplicate key values in i, each of which join to the same group in x over and over again. If that's ok, try including `j` and dropping `by` (by-without-by) so that j runs for each group to avoid the large allocation. If you are sure you wish to proceed, rerun with allow.cartesian=TRUE. Otherwise, please search for this error message in the FAQ, Wiki, Stack Overflow and datatable-help for advice.
Calls: [ -> [.data.table -> vecseq
what am I doing wrong?
PS. I am amenable to any alternative way to get the results; what is the most idiomatic way to do what I want (dt
must still be a data.table
, but id2name
can be anything mapping int to something else - as long as the int is not assumed to be a vector index).