The default argument to nomatch is `'getOption("datatable.nomatch")`. The
default value for this is `NA`.
If you want to change this option, simply set `options(datatable.nomatch = 0)`,
then the default will be as you want.
I think the current datatable.nomatch = NA is reasonable, as you are often
interested in non-matches as well as matches.
x[y, nomatch=NA] to give a error in your case, then follow the advice of the
error message and run
x[y, nomatch=NA, allow.cartesian = TRUE]
________________________________
From: [email protected]
[[email protected]] on behalf of Frank
Erickson [[email protected]]
Sent: Monday, 14 October 2013 1:03 PM
To: data.table source forge
Subject: [datatable-help] possible FR: in x[y], switch to nomatch=0 instead of
failing with "Error in vecseq..."
I don't know if this error shows up in other cases, but I always see it when
I'm about to do
x[y,b:=b]
but first want to check how
x[y]
looks before creating or overwriting x$b. Here's an example:
x <- data.table(a=rep(2:3,2),key='a')
y <- data.table(a=1:4,b=4:1,key='a')
x[y] # error
x[y,nomatch=0] # ok
x[y,b:=b] # ok
I'd prefer to see the first attempt mapped to the second (with a suitable
message), instead of erroring out. What do you all think? Is that
reasonable/worthwhile?
Best,
Frank
P.S. One other point, regarding the message itself (reproduced down below): I
don't understand why repeated values in i are mentioned.
-- For x[y] in my example, the problem seems to be coming from x having
repeated rows, not i (y in this case);
-- whereas y[x] works just fine (despite the repeated/duplicated values in
i...which is x here).
Error in vecseq(f__, len__, if (allow.cartesian) NULL else
as.integer(max(nrow(x), :
Join results in 6 rows; more than 4 = 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.
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