>>>>> Suharto Anggono Suharto Anggono via R-devel
>>>>> on Sun, 22 Feb 2026 03:58:13 +0000 (UTC) writes:
> diff(m, lag, dif) for matrix m now still returns
> matrices, also when lag * dif > nrow(m) (PR#18972, thanks to
> Mikael Jagan and Suharto Anggono).
> diff(<ts-matrix>) remains matrix, even when it has length zero.
> The above NEWS item has been moved to "CHANGES IN R 4.5.2 patched".
> In fact, in R-4-5-branch, diff(m, lag, dif) for matrix m is still not a
matrix when lag * dif > nrow(m) (see
https://svn.r-project.org/R/branches/R-4-5-branch/src/library/base/R/diff.R for
'diff.default';
https://svn.r-project.org/R/branches/R-4-5-branch/src/library/base/R/datetime.R
for 'diff.POSIXt';
https://svn.r-project.org/R/branches/R-4-5-branch/src/library/base/R/dates.R
for 'diff.Date';
https://svn.r-project.org/R/branches/R-4-5-branch/src/library/stats/R/ts.R for
'diff.ts').
> And I suggest keeping it so. Because it has been like that simce the
beginning, I think changing it in a patch release is not appropriate.
We have ported bug fixes of "forever bugs" to the "R patched
branch", before, quite on purpose.
Typically they have been really rare use cases and for that
reason probably were not detected and reported earlier... and we
(R core) still thought these bugs should disappear as quickly as
possible.
For the above reason(s), I *had* actually planned to port this bug
fix also to R "4.5.2 patched" ...
But then it has become somewhat late to do the port only now,
and R 4.5.3 will only be a "wrap up" release anyway..
Hence, I agree with your opinion and will now move the NEWS
entry instead of porting the bug fix which was the original plan.
Martin
> What have been ported to R-4-5-branch are just- replacing 'tsLag' with
'lag' in 'diff.ts'- 'Ops.ts' to return matrix when e1 or e2 is matrix but e1
and e2 are not overlapping
> I suggest reverting the port. A justification of diff(m) for 1-row ts
matrix m not being a matrix was that m - lag(m, -1) was not a matrix.
> Replacing 'tsLag' with 'lag' in 'diff.ts' is actually OK, but not
necessary.
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