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Bill Dunlap

2021-Jun-29 16:43 UTC

[Rd] ALTREP ALTINTEGER_SUM/MIN/MAX Return Value and Behavior

Adding the dimensions attribute takes away the altrep-ness.  Removing
dimensions
does not make it altrep.  E.g.,
> a <- 1:10
> am <- a ; dim(am) <- c(2L,5L)
> amn <- am ; dim(amn) <- NULL
> .Call("is_altrep", a)
[1] TRUE> .Call("is_altrep", am)
[1] FALSE> .Call("is_altrep", amn)[1] FALSE

where is_altrep() is defined by the following C code:

#include <R.h>
#include <Rinternals.h>

SEXP is_altrep(SEXP x)
{
    return Rf_ScalarLogical(ALTREP(x));
}

-Bill

On Tue, Jun 29, 2021 at 8:03 AM Sebastian Martin Krantz <
sebastian.krantz at graduateinstitute.ch> wrote:
> Hello together, I'm working on some custom (grouped, weighted) sum, min
and
> max functions and I want them to support the special case of plain integer
> sequences using ALTREP. I thereby encountered some behavior I cannot
> explain to myself. The head of my fsum C function looks like this (g is
> optional grouping vector, w is optional weights vector):
>
> SEXP fsumC(SEXP x, SEXP Rng, SEXP g, SEXP w, SEXP Rnarm) {
>   int l = length(x), tx = TYPEOF(x), ng = asInteger(Rng),
>     narm = asLogical(Rnarm), nprotect = 1, nwl = isNull(w);
>   if(ALTREP(x) && ng == 0 && nwl) {
>     switch(tx) {
>     case INTSXP: return ALTINTEGER_SUM(x, (Rboolean)narm);
>     case LGLSXP: return ALTLOGICAL_SUM(x, (Rboolean)narm);
>     case REALSXP: return ALTLOGICAL_SUM(x, (Rboolean)narm);
>     default: error("ALTREP object must be integer or real
typed");
>     }
>   }
> // ...
> }
>
> when I let x <- 1:1e8, fsum(x) works fine and returns the correct value.
If
> I now make this a matrix dim(x) <- c(1e2, 1e6) and subsequently turn
this
> into a vector again, dim(x) <- NULL, fsum(x) gives  NULL and a warning
> message 'converting NULL pointer to R NULL'. For functions fmin and
fmax
> (similarly defined using ALTINTEGER_MIN/MAX), I get this error right away
> e.g. fmin(1:1e8) gives NULL and warning 'converting NULL pointer to R
> NULL'. So what is going on here? What do these functions return? And
how do
> I make this a robust implementation?
>
> Best regards,
>
> Sebastian Krantz
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
	[[alternative HTML version deleted]]

Sebastian Martin Krantz

2021-Jun-29 16:56 UTC

head link

[Rd] ALTREP ALTINTEGER_SUM/MIN/MAX Return Value and Behavior

Thanks both. Is there a suggested way I can get this speedup in a package?
Or just leave it for now?

Thanks also for the clarification Bill. The issue I have with that is that
in my C code ALTREP(x) evaluates to true even after adding and removing
dimensions (otherwise it would be handled by the normal sum method and I?d
be fine). Also .Internal(inspect(x)) still shows the compact
representation.

-Sebastian

On Tue 29. Jun 2021 at 19:43, Bill Dunlap <williamwdunlap at gmail.com>
wrote:
> Adding the dimensions attribute takes away the altrep-ness.  Removing
> dimensions
> does not make it altrep.  E.g.,
>
> > a <- 1:10
> > am <- a ; dim(am) <- c(2L,5L)
> > amn <- am ; dim(amn) <- NULL
> > .Call("is_altrep", a)
> [1] TRUE
> > .Call("is_altrep", am)
> [1] FALSE
> > .Call("is_altrep", amn)
> [1] FALSE
>
> where is_altrep() is defined by the following C code:
>
> #include <R.h>
> #include <Rinternals.h>
>
> SEXP is_altrep(SEXP x)
> {
>     return Rf_ScalarLogical(ALTREP(x));
> }
>
>
> -Bill
>
> On Tue, Jun 29, 2021 at 8:03 AM Sebastian Martin Krantz <
> sebastian.krantz at graduateinstitute.ch> wrote:
>
>> Hello together, I'm working on some custom (grouped, weighted) sum,
min
>> and
>> max functions and I want them to support the special case of plain
integer
>> sequences using ALTREP. I thereby encountered some behavior I cannot
>> explain to myself. The head of my fsum C function looks like this (g is
>> optional grouping vector, w is optional weights vector):
>>
>> SEXP fsumC(SEXP x, SEXP Rng, SEXP g, SEXP w, SEXP Rnarm) {
>>   int l = length(x), tx = TYPEOF(x), ng = asInteger(Rng),
>>     narm = asLogical(Rnarm), nprotect = 1, nwl = isNull(w);
>>   if(ALTREP(x) && ng == 0 && nwl) {
>>     switch(tx) {
>>     case INTSXP: return ALTINTEGER_SUM(x, (Rboolean)narm);
>>     case LGLSXP: return ALTLOGICAL_SUM(x, (Rboolean)narm);
>>     case REALSXP: return ALTLOGICAL_SUM(x, (Rboolean)narm);
>>     default: error("ALTREP object must be integer or real
typed");
>>     }
>>   }
>> // ...
>> }
>>
>> when I let x <- 1:1e8, fsum(x) works fine and returns the correct
value.
>> If
>> I now make this a matrix dim(x) <- c(1e2, 1e6) and subsequently turn
this
>> into a vector again, dim(x) <- NULL, fsum(x) gives  NULL and a
warning
>> message 'converting NULL pointer to R NULL'. For functions fmin
and fmax
>> (similarly defined using ALTINTEGER_MIN/MAX), I get this error right
away
>> e.g. fmin(1:1e8) gives NULL and warning 'converting NULL pointer to
R
>> NULL'. So what is going on here? What do these functions return?
And how
>> do
>> I make this a robust implementation?
>>
>> Best regards,
>>
>> Sebastian Krantz
>>
>>         [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-devel at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>
	[[alternative HTML version deleted]]

iuke-tier@ey m@iii@g oii uiow@@edu

2021-Jun-29 17:54 UTC

head link

[Rd] [External] Re: ALTREP ALTINTEGER_SUM/MIN/MAX Return Value and Behavior

It depends on the size. For a larger vector adding dim will create a
wrapper ALTREP.

Currently the wrapper does not try to use the payload's sum method;
this could be added.

Best,

luke

On Tue, 29 Jun 2021, Bill Dunlap wrote:
> Adding the dimensions attribute takes away the altrep-ness.  Removing
> dimensions
> does not make it altrep.  E.g.,
>
>> a <- 1:10
>> am <- a ; dim(am) <- c(2L,5L)
>> amn <- am ; dim(amn) <- NULL
>> .Call("is_altrep", a)
> [1] TRUE
>> .Call("is_altrep", am)
> [1] FALSE
>> .Call("is_altrep", amn)
> [1] FALSE
>
> where is_altrep() is defined by the following C code:
>
> #include <R.h>
> #include <Rinternals.h>
>
> SEXP is_altrep(SEXP x)
> {
>    return Rf_ScalarLogical(ALTREP(x));
> }
>
> -Bill
>
> On Tue, Jun 29, 2021 at 8:03 AM Sebastian Martin Krantz <
> sebastian.krantz at graduateinstitute.ch> wrote:
>
>> Hello together, I'm working on some custom (grouped, weighted) sum,
min and
>> max functions and I want them to support the special case of plain
integer
>> sequences using ALTREP. I thereby encountered some behavior I cannot
>> explain to myself. The head of my fsum C function looks like this (g is
>> optional grouping vector, w is optional weights vector):
>>
>> SEXP fsumC(SEXP x, SEXP Rng, SEXP g, SEXP w, SEXP Rnarm) {
>>   int l = length(x), tx = TYPEOF(x), ng = asInteger(Rng),
>>     narm = asLogical(Rnarm), nprotect = 1, nwl = isNull(w);
>>   if(ALTREP(x) && ng == 0 && nwl) {
>>     switch(tx) {
>>     case INTSXP: return ALTINTEGER_SUM(x, (Rboolean)narm);
>>     case LGLSXP: return ALTLOGICAL_SUM(x, (Rboolean)narm);
>>     case REALSXP: return ALTLOGICAL_SUM(x, (Rboolean)narm);
>>     default: error("ALTREP object must be integer or real
typed");
>>     }
>>   }
>> // ...
>> }
>>
>> when I let x <- 1:1e8, fsum(x) works fine and returns the correct
value. If
>> I now make this a matrix dim(x) <- c(1e2, 1e6) and subsequently turn
this
>> into a vector again, dim(x) <- NULL, fsum(x) gives  NULL and a
warning
>> message 'converting NULL pointer to R NULL'. For functions fmin
and fmax
>> (similarly defined using ALTINTEGER_MIN/MAX), I get this error right
away
>> e.g. fmin(1:1e8) gives NULL and warning 'converting NULL pointer to
R
>> NULL'. So what is going on here? What do these functions return?
And how do
>> I make this a robust implementation?
>>
>> Best regards,
>>
>> Sebastian Krantz
>>
>>         [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-devel at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
-- 
Luke Tierney
Ralph E. Wareham Professor of Mathematical Sciences
University of Iowa                  Phone:             319-335-3386
Department of Statistics and        Fax:               319-335-3017
    Actuarial Science
241 Schaeffer Hall                  email:   luke-tierney at uiowa.edu
Iowa City, IA 52242                 WWW:  http://www.stat.uiowa.edu

R devel - Jun 2021 - ALTREP ALTINTEGER_SUM/MIN/MAX Return Value and Behavior

[Rd] ALTREP ALTINTEGER_SUM/MIN/MAX Return Value and Behavior

[Rd] ALTREP ALTINTEGER_SUM/MIN/MAX Return Value and Behavior

[Rd] [External] Re: ALTREP ALTINTEGER_SUM/MIN/MAX Return Value and Behavior