Re: [Rcpp-devel] Deriving type information
In addition to what Kevin said, perhaps you are looking for macros from this
file:
https://github.com/RcppCore/Rcpp/blob/master/inst/include/Rcpp/macros/dispatch.h
Le 14 févr. 2014 à 00:34, Søren Højsgaard a écrit :
> Dear all,
>
> Function foo_num below takes a numeric vector and returns a list with the
> first element of the vector. (Not very interesting function). I want to
> create a templated version of this in function do_foo below, but whether "a"
> should be a double, an integer, or a string depends on the RTYPE.
>
> My question is (and it is embarrasing to ask because I believe Romain has
> already answered it; just can't find the answer) how to derive the what type
> "a" should have once we know RTYPE??
>
> My second question is: Isn't there an easier general way to write the
> dispatch function (I have in mind situations where the templated function
> takes *more* than one argument!)? I have in mind something like:
>
> int type = TYPEOF(XX_) ;
> return do_foo ( XX_ ) ;
>
> but that fails because INTSXP, REALSXP etc seems to be defined as const's
> (thats my reading of the compiler message).
What goes into template parameters is compile time constant. And the type of an
R object is dynamic, there is no way to know before runtime, so the compiler
can not do this for you.
>
> Thanks
> Søren
>
>
> #include
> using namespace Rcpp;
> //[[Rcpp::export]]
> List foo_num(NumericVector x){
> double a=x[0];
> return List::create( a );
> }
>
> template
> List do_foo( Vector x ){
> double a=x[0]; // WHAT TO DO HERE???
> return List::create( a );
> }
>
> SEXP foo_any( SEXP& XX_){
> int type = TYPEOF(XX_) ;
> switch( type ){
> case INTSXP : return do_foo ( XX_ ) ;
> case REALSXP : return do_foo( XX_ ) ;
> case STRSXP : return do_foo ( XX_ ) ;
> }
> return R_NilValue ;
> }
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Re: [Rcpp-devel] Deriving type information
Hi Søren, You want to use Rcpp's traits. I don't think these are explicitly documented anywhere, although there are a few examples on the gallery demonstrating their usage (e.g. http://gallery.rcpp.org/articles/top-elements-from-vectors-using-priority-queue/) In this case, you can use traits::storage_type::type to extract the type. Typically, using a typedef makes it easiest, so I would write something like: typedef typename traits::storage_type::type storage_t; storage_t a = x[0]; Once you understand the general pattern, it's pretty easy to just read and understand the traits available at https://github.com/RcppCore/Rcpp/tree/master/inst/include/Rcpp/traits, but perhaps this would be a good gallery post. For more information, I thought this was a pretty good introductory article on understanding C++ traits: http://accu.org/index.php/journals/442 Cheers, Kevin ___ Rcpp-devel mailing list Rcpp-devel@lists.r-forge.r-project.org https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
[Rcpp-devel] Deriving type information
Dear all,
Function foo_num below takes a numeric vector and returns a list with the first
element of the vector. (Not very interesting function). I want to create a
templated version of this in function do_foo below, but whether "a" should be a
double, an integer, or a string depends on the RTYPE.
My question is (and it is embarrasing to ask because I believe Romain has
already answered it; just can't find the answer) how to derive the what type
"a" should have once we know RTYPE??
My second question is: Isn't there an easier general way to write the dispatch
function (I have in mind situations where the templated function takes *more*
than one argument!)? I have in mind something like:
int type = TYPEOF(XX_) ;
return do_foo ( XX_ ) ;
but that fails because INTSXP, REALSXP etc seems to be defined as const's
(thats my reading of the compiler message).
Thanks
Søren
#include
using namespace Rcpp;
//[[Rcpp::export]]
List foo_num(NumericVector x){
double a=x[0];
return List::create( a );
}
template
List do_foo( Vector x ){
double a=x[0]; // WHAT TO DO HERE???
return List::create( a );
}
SEXP foo_any( SEXP& XX_){
int type = TYPEOF(XX_) ;
switch( type ){
case INTSXP : return do_foo ( XX_ ) ;
case REALSXP : return do_foo( XX_ ) ;
case STRSXP : return do_foo ( XX_ ) ;
}
return R_NilValue ;
}
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Re: [Rcpp-devel] conditionally created vectors
On 13 February 2014 at 18:26, Hideyoshi Maeda wrote:
| So I’m guessing there is no simple export outside of the {} function?
Wrong. You can also do this, relying on the Rcpp vector constructor:
#include
// [[Rcpp::export]]
Rcpp::NumericVector f2(std::string typ){
Rcpp::NumericVector xx;
if (typ=="nc"){
xx = Rcpp::NumericVector(10);
} else {
xx = Rcpp::NumericVector(20);
}
return xx;
}
This is pretty basic C / C++ so you may want to go back and revisit some of
your books.
Dirk
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Re: [Rcpp-devel] conditionally created vectors
The way around it is to declare 'xx' in the parent scope, and then assign
to it directly, e.g.
// [[Rcpp::export]]
Rcpp::NumericVector f1(String typ){
Rcpp::NumericVector xx;
if(typ=="nc"){
xx = Rcpp::NumericVector(10);
} else {
xx = Rcpp::NumericVector(20);
}
return xx;
}
'Technically', the object 'xx' will be default initialized when declared
like that, but the compiler can optimize that away.
Cheers,
Kevin
On Thu, Feb 13, 2014 at 10:26 AM, Hideyoshi Maeda wrote:
> So I'm guessing there is no simple export outside of the {} function?
> On 13 Feb 2014, at 18:17, Dirk Eddelbuettel wrote:
>
> >
> > On 13 February 2014 at 17:48, Hideyoshi Maeda wrote:
> > | Dear Rcpp-Devel list,
> > |
> > | I am relatively new to Rcpp and am struggling to work out why the
> following code does not compile.
> > |
> > | #include
> > | using namespace Rcpp;
> > |
> > | // [[Rcpp::export]]
> > | Rcpp::NumericVector f1(String typ){
> > | if(typ=="nc"){
> > | Rcpp::NumericVector xx(10);
> > | } else {
> > | Rcpp::NumericVector xx(20);
> > | }
> > | return xx;
> > | }
> >
> > "Scope".
> >
> > You create 'xx' inside the { } and it does not exist outside of those.
> >
> > | Basically the function takes in a string input and if its has the
> value "nc" then it returns a zero string of length 10 and if it doesn't
> then it should return a zero vector of length 20. I don't quite understand
> why the above code works but the below code does. What do I need to do to
> make the above code work, so that I can call xx after the if statement is
> done?
> > |
> > | #include
> > | using namespace Rcpp;
> > |
> > | // [[Rcpp::export]]
> > | Rcpp::NumericVector f1(String typ){
> > | if(typ=="nc"){
> > | Rcpp::NumericVector xx(10);
> > | return xx;
> > | } else {
> > | Rcpp::NumericVector xx(20);
> > | return xx;
> > | }
> > | }
> >
> > Try this. It uses RcppArmadillo which has a resize() member function.
> >
> >
> > // [[Rcpp::depends(RcppArmadillo)]]
> >
> > #include
> >
> >
> > // [[Rcpp::export]]
> > arma::colvec f1(std::string typ){
> > arma::colvec xx;
> > if (typ=="nc"){
> >xx.resize(10);
> > } else {
> >xx.resize(20);
> > }
> > return xx;
> > }
> >
> > Dirk
> >
> > --
> > Dirk Eddelbuettel | e...@debian.org | http://dirk.eddelbuettel.com
>
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Re: [Rcpp-devel] conditionally created vectors
So I’m guessing there is no simple export outside of the {} function?
On 13 Feb 2014, at 18:17, Dirk Eddelbuettel wrote:
>
> On 13 February 2014 at 17:48, Hideyoshi Maeda wrote:
> | Dear Rcpp-Devel list,
> |
> | I am relatively new to Rcpp and am struggling to work out why the following
> code does not compile.
> |
> | #include
> | using namespace Rcpp;
> |
> | // [[Rcpp::export]]
> | Rcpp::NumericVector f1(String typ){
> | if(typ=="nc"){
> | Rcpp::NumericVector xx(10);
> | } else {
> | Rcpp::NumericVector xx(20);
> | }
> | return xx;
> | }
>
> "Scope".
>
> You create 'xx' inside the { } and it does not exist outside of those.
>
> | Basically the function takes in a string input and if its has the value
> “nc” then it returns a zero string of length 10 and if it doesn’t then it
> should return a zero vector of length 20. I don’t quite understand why the
> above code works but the below code does. What do I need to do to make the
> above code work, so that I can call xx after the if statement is done?
> |
> | #include
> | using namespace Rcpp;
> |
> | // [[Rcpp::export]]
> | Rcpp::NumericVector f1(String typ){
> | if(typ=="nc"){
> | Rcpp::NumericVector xx(10);
> | return xx;
> | } else {
> | Rcpp::NumericVector xx(20);
> | return xx;
> | }
> | }
>
> Try this. It uses RcppArmadillo which has a resize() member function.
>
>
> // [[Rcpp::depends(RcppArmadillo)]]
>
> #include
>
>
> // [[Rcpp::export]]
> arma::colvec f1(std::string typ){
> arma::colvec xx;
> if (typ=="nc"){
>xx.resize(10);
> } else {
>xx.resize(20);
> }
> return xx;
> }
>
> Dirk
>
> --
> Dirk Eddelbuettel | e...@debian.org | http://dirk.eddelbuettel.com
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Re: [Rcpp-devel] conditionally created vectors
On 13 February 2014 at 17:48, Hideyoshi Maeda wrote:
| Dear Rcpp-Devel list,
|
| I am relatively new to Rcpp and am struggling to work out why the following
code does not compile.
|
| #include
| using namespace Rcpp;
|
| // [[Rcpp::export]]
| Rcpp::NumericVector f1(String typ){
| if(typ=="nc"){
| Rcpp::NumericVector xx(10);
| } else {
| Rcpp::NumericVector xx(20);
| }
| return xx;
| }
"Scope".
You create 'xx' inside the { } and it does not exist outside of those.
| Basically the function takes in a string input and if its has the value “nc”
then it returns a zero string of length 10 and if it doesn’t then it should
return a zero vector of length 20. I don’t quite understand why the above code
works but the below code does. What do I need to do to make the above code
work, so that I can call xx after the if statement is done?
|
| #include
| using namespace Rcpp;
|
| // [[Rcpp::export]]
| Rcpp::NumericVector f1(String typ){
| if(typ=="nc"){
| Rcpp::NumericVector xx(10);
| return xx;
| } else {
| Rcpp::NumericVector xx(20);
| return xx;
| }
| }
Try this. It uses RcppArmadillo which has a resize() member function.
// [[Rcpp::depends(RcppArmadillo)]]
#include
// [[Rcpp::export]]
arma::colvec f1(std::string typ){
arma::colvec xx;
if (typ=="nc"){
xx.resize(10);
} else {
xx.resize(20);
}
return xx;
}
Dirk
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[Rcpp-devel] conditionally created vectors
Dear Rcpp-Devel list,
I am relatively new to Rcpp and am struggling to work out why the following
code does not compile.
#include
using namespace Rcpp;
// [[Rcpp::export]]
Rcpp::NumericVector f1(String typ){
if(typ=="nc"){
Rcpp::NumericVector xx(10);
} else {
Rcpp::NumericVector xx(20);
}
return xx;
}
Basically the function takes in a string input and if its has the value “nc”
then it returns a zero string of length 10 and if it doesn’t then it should
return a zero vector of length 20. I don’t quite understand why the above code
works but the below code does. What do I need to do to make the above code
work, so that I can call xx after the if statement is done?
#include
using namespace Rcpp;
// [[Rcpp::export]]
Rcpp::NumericVector f1(String typ){
if(typ=="nc"){
Rcpp::NumericVector xx(10);
return xx;
} else {
Rcpp::NumericVector xx(20);
return xx;
}
}
thank
HLM
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Re: [Rcpp-devel] Extending Rcpp with a dummy class
On 13 February 2014 at 15:55, Alessandro Mammana wrote:
| Suppose that for any reason I want to define my own vector class like this:
|
| template
| struct Vec {
| T* ptr;
| int len;
| };
Conceptually that is about the same as our vectors.
| so, without owning memory but just pointing to some (hopefully valid)
| area of memory.
| How can I extend Rcpp with this class so that I can have R vectors
| automatically converted to these vectors?
| The obvious answer is "read "extending Rcpp" instead of bothering us",
Precisely. :)
And look at the working examples, eg on the Rcpp Gallery I have posts doing
this for Boost DateTime, and for sparse Armadillo matrices. Look at other
packages. The most full-featured are probably RcppArmadillo and RcppEigen.
| but the compiler complains and says:
| error: 'Vector' is not a member of 'Rcpp'
|
| this is probably because I still did not import Rcpp.h, but in
Correct.
| "extending Rcpp" they say to include Rcpp.h only after defining my
| classes, so how should I do?
Re-read it. You misunderstood that statement. RcppCommon is used for some
forward declarations. You use it here to replace Rcpp.h. Won't work.
Dirk
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[Rcpp-devel] Extending Rcpp with a dummy class
Dear all,
I have another one of my stupid questions.
Suppose that for any reason I want to define my own vector class like this:
@
template
struct Vec {
T* ptr;
int len;
};
@
so, without owning memory but just pointing to some (hopefully valid)
area of memory.
How can I extend Rcpp with this class so that I can have R vectors
automatically converted to these vectors?
The obvious answer is "read "extending Rcpp" instead of bothering us",
and I did it, and I tried the following:
@
#include
template
struct Vec {
T* ptr;
int len;
Vec(SEXP x){
if (TYPEOF(x) != Rcpp::traits::r_sexptype_traits::rtype)
Rcpp::stop("incompatible types");
Rcpp::Vector< Rcpp::traits::r_sexptype_traits::rtype > rcpp_vec(x);
ptr = rcpp_vec.begin();
len = rcpp_vec.length();
}
};
#include
blablabla
@
but the compiler complains and says:
error: 'Vector' is not a member of 'Rcpp'
this is probably because I still did not import Rcpp.h, but in
"extending Rcpp" they say to include Rcpp.h only after defining my
classes, so how should I do?
Thanks in advance!
Ale
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Re: [Rcpp-devel] filling in blocks of a matrix
On 13 February 2014 at 11:23, Hideyoshi Maeda wrote: | I am looking to see it is possible to fill in a matrix with another matrix. | | I have three matrices, out1 which is a 5x5 zero matrix | | out2 is a 3x3 matrix with each value set as 8 | | and out3 which is a 5x4 matrix with each value set as 9 | | I would like to change part of my out1 matrix by filling it with the values in out2 or out3, is this possible? I would do that in Armadillo via RcppArmadillo -- as Armadillo has a number of sub-matrix views, subsetters and assignments. Dirk -- Dirk Eddelbuettel | e...@debian.org | http://dirk.eddelbuettel.com ___ Rcpp-devel mailing list Rcpp-devel@lists.r-forge.r-project.org https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
[Rcpp-devel] filling in blocks of a matrix
Dear Rcpp-List,
I am looking to see it is possible to fill in a matrix with another matrix.
I have three matrices, out1 which is a 5x5 zero matrix
out2 is a 3x3 matrix with each value set as 8
and out3 which is a 5x4 matrix with each value set as 9
I would like to change part of my out1 matrix by filling it with the values in
out2 or out3, is this possible?
Would I just need to use loops to sequentially fill it in (either row by row or
column by column etc)? or could I just assign new values to the bits i want to
change?
Below is my attempt at doing the later, but it does not compile saying that for
this line "out1(Range(0,2),Range(1,3)) = out2;” there is no viable overload ‘='
Perhaps this is rather simple but I am very new to Rcpp, but any help would be
much appreciated.
Regards
HLM
#include
using namespace Rcpp;
// [[Rcpp::export]]
Rcpp::NumericMatrix f1(String h){
String h1 = h;
NumericMatrix out1(5,5);
NumericMatrix out2(3,3);
NumericMatrix out3(5,4);
std::fill(out2.begin(), out2.end(), 8);
std::fill(out3.begin(), out2.end(), 9);
if(h1=="nc"){
out1(Range(0,2),Range(1,3)) = out2;
} else {
out1(_,Range(1,4)) = out3;
}
return out1;
}
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