In principle, I agree that faster ranking/sorting algorithms are
important, and should be a priority.
But I can't help but feel that the paper focuses on textbook-oriented problems.
Given that in real world problems, there's almost always some form of
prior knowledge:
Wouldn't it be better, from a
Abby,
Vectors do have an internal mechanism for knowing that they are sorted via
ALTREP (it was one of 2 core motivating features for 'smart vectors' the
other being knowledge about presence of NAs).
Currently I don't think we expose it at the R level, though it is part of
the official C API. I d
Thanks Simon. I missed that. It is a sensible change.
I had trouble because I had just changed computing environments this weekend (a
forced
change due to an institutional directive), and this caught me right after that
so I spent
some time chasing my tail. Murphy's law...
Terry T.
On 3/
Terry,
NEWS: CHANGES IN R 4.0.0 NEW FEATURES
\item S3 method lookup now by default skips the elements of the
search path between the global and base environments.
If you use attach(), S3 methods are hence no longer dispatched to (because it
is between global and base) unless you regi
Hi Abby,
Thank you for your positive feedback.
I agree for your general comment about sorting.
For ave specifically, ordering may not help because the output must maintain
the order of the input (as ave returns only x and not the entiere data.frame).
Thanks,
Thomas
___
This change in R-devel just bit me. Under the newest release, if I attach()
another
.RData directory, the methods are not detected.
Was it intentional? Running in Linux. Here is a script of an example that
works fine
under 3.6.2. but fails in R-devel.
tmt% mkdir temp1
tmt% cd temp1
tmt%
Default method for sort is not radix(especially for character vector). You
might want to read the documentation of sort.
For your second question, I invite you to look at the code of fsort. It is
implemented only for positive finite double, and default to
data.table:::forder ... when the types are
Isn’t the default method now “radix” which is the data.table sort, and
isn’t that already parallel using openmp where available?
Avi
On Mon, Mar 15, 2021 at 12:26 PM Morgan Morgan
wrote:
> Hi,
> I am not sure if this is the right mailing list, so apologies in advance if
> it is not.
>
> I found
Hi,
I am not sure if this is the right mailing list, so apologies in advance if
it is not.
I found the following link/presentation:
https://www.r-project.org/dsc/2016/slides/ParallelSort.pdf
The implementation of fsort is interesting but incomplete (not sure why?)
and can be improved or made fast
Hi Thomas,
These are some great suggestions.
But I can't help but feel there's a much bigger problem here.
Intuitively, the ave function could (or should) sort the data.
Then the indexing step becomes almost trivial, in terms of both time
and space complexity.
And the ave function is not the only
On 3/12/21 7:43 PM, xiaoyan yu wrote:
I am writing C++ program based on R extensions and also try to test the
program with google address sanitizer.
I thought if I don't protect the variable from the allocation API such as
Rf_allocVector, there will be a memory leak. However, the address sanitiz
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