[Rcpp-devel] Ranges and Casting

Sat Jan 16 22:08:06 CET 2021

Yes, it helps a lot.

This confirms that I've been doing the right workarounds in my code. I
thought there was a better way of doing it :-)

Best regards!

PS: today I've learned how to strip debug info using Makevars, thanks @Dirk
Eddelbuettel <edd at debian.org>  :)

--
Francisco Bischoff, MD, MSc
Faculty of Medicine of the University of Porto, Portugal

- Master of Medical Informatics | topic: time series
- Research Associate | artificial intelligence for health
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| CiênciaID B413-E0A0-DE8D | LinkedIn: franzbischoff

On Sat, Jan 16, 2021 at 7:26 PM Balamuta, James Joseph <
balamut2 at illinois.edu> wrote:

> Francisco,
>
>
>
> Based on the opening post, I’d probably push you more toward Armadillo as
> Dirk was in the previous message. Using linspace<>(), may be a drop-in
> replacement for seq() with the appropriate helper functions. Long ago (~4+
> years now) I wrote a few, see:
>
>
>
> https://github.com/coatless/r-to-armadillo/blob/master/src/seq.cpp
> <https://mailtrack.io/trace/link/80d9c725d261dfb303ccd7ab084979cdd2470c1b?url=https%3A%2F%2Fgithub.com%2Fcoatless%2Fr-to-armadillo%2Fblob%2Fmaster%2Fsrc%2Fseq.cpp&userId=3785237&signature=71713cb13a1d39e3>
>
>
>
> That said, Range is definitely preferred inside of subsets operations into
> Rcpp-like data structures. However, the subset and assign operation is a
> bit problematic with template expansion. So, the given example needs to
> have an intermediary:
>
>
>
>   // Initialization:
>
>   Rcpp::NumericVector my_vec = Rcpp::NumericVector::create(1, 2, 3, 4, 5,
> 6);
>
>
>
>   // Subset and Assign to 5:
>
>   Rcpp::IntegerVector subset_idx = Rcpp::Range(0, 3);
>
>   my_vec[subset_idx] = 20;
>
>
>
>   // Subset Positions:
>
>  Rcpp::NumericVector subset_result = my_vec[Rcpp::Range(4, 5)];
>
>
>
> Hope it helps.
>
>
>
> Best,
>
>
>
> JJB
>
>
>
> *From: *Rcpp-devel <rcpp-devel-bounces at lists.r-forge.r-project.org> on
> behalf of Francisco Bischoff <fbischoff at med.up.pt>
> *Date: *Friday, January 15, 2021 at 8:05 PM
> *To: *Dirk Eddelbuettel <edd at debian.org>
> *Cc: *"rcpp-devel at lists.r-forge.r-project.org" <
> rcpp-devel at lists.r-forge.r-project.org>
> *Subject: *Re: [Rcpp-devel] Ranges and Casting
>
>
>
> Thanks for the tips.
>
>
>
> Still, Range() is the correct way to write:
>
>
>
> NumericVector my_vec(200);
>
>
>
> my_vec(Range(0,10)) = 10;
>
>
>
> ?
>
>
>
> Thanks in advance
>
>
>
>
>
>
>
>
> --
> Francisco Bischoff, MD, MSc
>
> Faculty of Medicine of the University of Porto, Portugal
>
>
>
> - Master of Medical Informatics | topic: time series
> - Research Associate | artificial intelligence for health
> <https://mailtrack.io/trace/link/81d202d5907c5004ac87fa7189a5f43096f298cb?url=https%3A%2F%2Furldefense.com%2Fv3%2F__https%3A%2Fmailtrack.io%2Ftrace%2Flink%2F1765b288bbce44d233e851a8d862ec594378aa04%3Furl%3Dhttp*3A*2F*2Fcintesis.eu*2Fai4health*2F%26userId%3D3785237%26signature%3D1b62d7a180130981__%3BJSUlJSU!!DZ3fjg!oa0yWHu4WaDeqycuBEcPRuw3vEvJrYARPPIAzJNsnxdet6loFCJ7O95nLR4ByfJyNzg%24&userId=3785237&signature=6f861a4b397dfc79>
> @ cintesis.eu
> <https://mailtrack.io/trace/link/5daf3fbe3ec2bde304cedb67b9c667f32b984de5?url=https%3A%2F%2Furldefense.com%2Fv3%2F__https%3A%2Fmailtrack.io%2Ftrace%2Flink%2F89b15c4212d5d6c8d4ba354ec92ab002ba9a96ef%3Furl%3Dhttp*3A*2F*2Fcintesis.eu%26userId%3D3785237%26signature%3D5fa97b31373fa664__%3BJSUl!!DZ3fjg!oa0yWHu4WaDeqycuBEcPRuw3vEvJrYARPPIAzJNsnxdet6loFCJ7O95nLR4B0QFIUzg%24&userId=3785237&signature=df96e330eb4e5915>
> - Teaching Assistant | department of community medicine, information and
> health decision sciences @ med.up.pt
> <https://mailtrack.io/trace/link/83fdd729acfe28d35a79adba75b6427b6c655131?url=https%3A%2F%2Furldefense.com%2Fv3%2F__https%3A%2Fmailtrack.io%2Ftrace%2Flink%2F32f5f446b7bc0d597241524764b3636b5a75d466%3Furl%3Dhttp*3A*2F*2Fmed.up.pt%26userId%3D3785237%26signature%3Dcfbca25f5fe210b3__%3BJSUl!!DZ3fjg!oa0yWHu4WaDeqycuBEcPRuw3vEvJrYARPPIAzJNsnxdet6loFCJ7O95nLR4BoT_L--M%24&userId=3785237&signature=cb0c4f80c0dd44f2>
>
> ORCID: 0000-0002-5301-8672 | Mendeley: francisco-bischoff | Google:
> tCeA0uUAAAAJ | ResearcherID: H-8261-2016 | ResearchGate: Francisco_Bischoff
> | CiênciaID B413-E0A0-DE8D | LinkedIn: franzbischoff
>
>
>
>
>
> On Sat, Jan 16, 2021 at 1:54 AM Dirk Eddelbuettel <edd at debian.org> wrote:
>
>
> On 16 January 2021 at 01:35, Francisco Bischoff wrote:
> | About the Range() function, I think it should handle decreasing ranges
> | too...
> | But, idk if using Matlabs approach or R approach:
> |
> | R's:
> |
> | a <- 1
> | b <- 10
> |
> | print(a:b)
> | 1 2 3 4 5 6 7 8 9 10
> | print(b:a)
> | 10 9 8 7 6 5 4 3 2 1
> |
> | Matlab's
> | a = 1;
> | b = 10;
> | disp(a:b);
> | 1 2 3 4 5 6 7 8 9 10
> | disp(b:a);
> | numeric(0)
> | disp(b:-1:a)
> | 10 9 8 7 6 5 4 3 2 1
> |
> | I think that we are in the R domain, so we should use Range(b, a)
> normally
> | (my humble opinion).
>
> Hm but I think the Range class in Rcpp is not the same as R's seq(). It is
> used internally in a few places and may not generalize well to the 'b:-1:a'
> use.
>
> I had a quick look, and Armadillo may not have anything directly relevant
> either. linspace() is close but not quite the same.
>
> I would probably just write myself a little helper function.
>
> | About Casting, this is a good example:
> |
> | Rcout << Range(0, 10) << std::endl;
> |
> | This does not compute...
> |
> | What should I do?
> |
> | Rcout << as<IntegerVector>(Range(0, 10)) << std::endl;
> | or
> | Rcout << (IntegerVector)(Range(0, 10)) << std::endl;
>
> That can happen as template expressions can get in the way. Alternatives
> are
> maybe using Armadillo types for, again, just using a quick loop and
> printing
> elements.
>
> Rcpp has a lot of functions. But it doesn't have "all of R's functions" and
> should not be seen as aiming for that.
>
> Dirk
>
> --
> https://dirk.eddelbuettel.com
> <https://mailtrack.io/trace/link/6980bfa152de9cac3c6fdf921fa97bf34670a814?url=https%3A%2F%2Furldefense.com%2Fv3%2F__https%3A%2Fmailtrack.io%2Ftrace%2Flink%2Fec16eaacf00108f6b925d8cd55d469ea736d3313%3Furl%3Dhttps*3A*2F*2Fdirk.eddelbuettel.com%26userId%3D3785237%26signature%3D5ff5161e5ff16475__%3BJSUl!!DZ3fjg!oa0yWHu4WaDeqycuBEcPRuw3vEvJrYARPPIAzJNsnxdet6loFCJ7O95nLR4BxG2v_1M%24&userId=3785237&signature=6c0196f400190f18>
> | @eddelbuettel | edd at debian.org
>
> [image: Image removed by sender.]
>
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