Hi,
Yes that warning was because Ricky supplied the output of dput to
create the example data, which uses structure(). Creating a data.table
that way doesn't initialize the .internal.selfref. I usually just
replace the structure() with a data.table() call when pasting code like
that.
Have now improved that warning :
" ... At an earlier point, this data.table has been copied by R (or
been created manually using structure() or similar). Avoid ..."
and the result looks correct to me in v1.8.7.
Thanks,
Matthew
On 21.01.2013 19:42, statquant3 wrote:
As Matthew is saying, I am using v.1.8.7 (lattest release)
I get a warning:
R> test.dt[, tc := which(name==order), by=list(ID, name)]
Warning message:
In `[.data.table`(test.dt, , `:=`(tc, which(name == order)), by =
list(ID,
:
Invalid .internal.selfref detected and fixed by taking a copy of
the whole
table, so that := can add this new column by reference. At an earlier
point,
this data.table has been copied by R. Avoid key<-, names<- and attr<-
which
in R currently (and oddly) may copy the whole data.table. Use set*
syntax
instead to avoid copying: setkey(), setnames() and setattr(). Also,
list(DT1,DT2) will copy the entire DT1 and DT2 (R's list() copies
named
objects), use reflist() instead if needed (to be implemented). If
this
message doesn't help, please report to datatable-help so the root
cause can
be fixed.
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