[Rcpp-devel] code explanation

[Kevin Ushey]

c1 is already defined, so you simply want

    c1 = as<NumericVector>(c1);

That is, when you write

    NumericVector c1 = as<NumericVector>(c1);

you are effectively trying to create a new NumericVector called `c1` -- but
since an object with the name `c1` already exists in scope, that fails.

Kevin

On Wed, Jun 10, 2015 at 11:09 AM guillaume chaumet <
guillaumechaumet at gmail.com> wrote:

> I found the explanation alone.
> The "list to data.frame" conversion was done by simply: returned_frame.
> attr("class") = "data.frame";
>
> This is my solution for a transposed data.frame
>
> ## The "R"code for the list:
>
> mylist=list(c("1" , "", "0" , "112.6336"),c("2" , "*" , "20" ,
> "113.0659"), c("3" , "" , "40" , "111.5833"),c("4" , "" , "60" ,"110.9704"))
>
>
> // The Cpp code
> #include <Rcpp.h>
>
> using namespace Rcpp;
>
> // [[Rcpp::export]]
> #include <Rcpp.h>
>
> using namespace Rcpp;
>
> // [[Rcpp::export]]
> List CheapDataFrameBuilder(List a) {
>     List returned_frame = clone(a);
>     StringVector c1(returned_frame.length());
>     StringVector c2(returned_frame.length());
>     StringVector c3(returned_frame.length());
>     StringVector c4(returned_frame.length());
>     StringVector vector(4);
>
>     for (int j = 0; j < returned_frame.length(); ++j) {
>         vector=returned_frame(j);
>         c1(j) = vector(0);
>         c2(j) = vector(1);
>         c3(j) = vector(2);
>         c4(j) = vector(3);
>     }
>     return Rcpp::DataFrame::create(Rcpp::Named("Frame")=c1,
>     Rcpp::Named("Sync")=c2,
>     Rcpp::Named("Time")=c3,
>     Rcpp::Named("Point_1")=c4);
> }
>
> Everything works, however I want to convert the first, the third and the
> forth vector into a NumericVector.
> I have try:
> NumericVector c1=as<NumericVector>(c1)
> from Hadley website but:
> error: redefinition of 'c1' with a different type: 'Vector<14>' vs
> 'Vector<16>'
>
> Did I miss something?
>
> Cheers
>
> G
>
>
> 2015-06-10 12:45 GMT+02:00 guillaume chaumet <guillaumechaumet at gmail.com>:
>
>> Dear List,
>> Could I have some explanation comments on this code:
>> https://github.com/jjallaire/rcpp-gallery/blob/gh-pages/src/2013-01-22-faster-data-frame-creation.cpp
>> ?
>> I just want to transpose the resulting data frame. However, I want to do
>> it myself but I don't understand the code.
>>
>> Thank you for your time
>>
>> Cheers
>>
>> Guillaume
>>
>
> _______________________________________________
> Rcpp-devel mailing list
> Rcpp-devel at lists.r-forge.r-project.org
> https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.r-forge.r-project.org/pipermail/rcpp-devel/attachments/20150610/eb6af770/attachment.html>