Displaying 3 results from an estimated 3 matches for "fastpass".
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2018 Apr 06
2
Part of fastpass in 'sort.list' can make sorting unstable
In the code of functions 'order' and 'sort.list' in R 3.5.0 alpha (in https://svn.r-project.org/R/branches/R-3-5-branch/src/library/base/R/sort.R), in "fastpass, take advantage of ALTREP metadata", there is "try the reverse since that's easy too...". If it succeeds, ties are reordered, violating stability of sorting.
Example:
x <- sort(c(1, 1, 3))
x # 1 1 3
sort.list(x, decreasing=TRUE) # should be 3 1 2
2018 May 08
1
Proposed speedup of ifelse
Hugh,
(Note I speak for myself only and not for R-core) Thanks for looking into
this. I think it's great to have community members that are interested in
contributing to R and helping it continue to get better.
And I think, and my local experiments bear out, that using anyNA as a
fastpass condition does allow us to get a significant speedup over what's
in there now. To do so, though, I took a somewhat different approach than
your proposal:
ifelse2 = function(test, yes, no) {
if (is.atomic(test)) {
if (typeof(test) != "logical")
storage.mode(tes...
2018 May 03
2
Proposed speedup of ifelse
> I propose a patch to ifelse that leverages anyNA(test) to achieve an
> improvement in performance. For a test vector of length 10, the change
> nearly halves the time taken and for a test of length 1 million, there
> is a tenfold increase in speed. Even for small vectors, the
> distributions of timings between the old and the proposed ifelse do
> not intersect.
For smaller