[Rcpp-devel] How to set stringsAsFactors=FALSE in Rcpp::DataFrame?

[Asis Hallab]

Dear Dirk,

many thanks for the provided solution.

Cheers!

2014-07-22 13:35 GMT+02:00 Dirk Eddelbuettel <edd at debian.org>:
>
> On 22 July 2014 at 12:59, Asis Hallab wrote:
> | Dear Rcpp-Experts,
> |
> | how can I get the equivalent of the R expression
> |
> | my.df <- data.frame( …, stringsAsFactors=FALSE )
> |
> | in Rcpp?
>
> The same way, but setting a variable name stringsAsFactors to FALSE, or
> rather its lowercase C++ equivalent.
>
> In cases like this it is a good idea to peruse the unit tests where you would
> have found
>
> // [[Rcpp::export]]
> DataFrame createTwoStringsAsFactors(){
>     IntegerVector v = IntegerVector::create(1,2,3);
>     std::vector<std::string> s(3);
>     s[0] = "a";
>     s[1] = "b";
>     s[2] = "c";
>     return DataFrame::create(_["a"] = v,
>                              _["b"] = s,
>                              _["stringsAsFactors"] = false );
> }
>
> I prefer Named("....") over _["..."] but it amounts to the same.
>
> Dirk
>
>
> |
> | I have this code in Rcpp:
> |    …
> |    return( DataFrame::create(
> |       Named( "acc" )       = accsCol,
> |       Named( "ec" )        = ecCol,
> |       Named( "prot.acc" )  = protCol,
> |       Named( "term_type" ) = termTypeCol
> |     ) );
> |
> | Calling the above from R, I realize, that the returned DataFrame's
> | columns are factors and not character-vectors, as I need them to be.
> |
> | How to achieve this?
> | Should I just convert them in R itself, like in the following example?
> |
> | for ( i in 1:ncol(my.df) ) {
> |   my.df[,i] <- as.character( my.df[,i] )
> | }
> |
> | Or is there a better - and possibly more efficient - way to achieve this?
> |
> | As always your help will be much appreciated.
> |
> | Have a pleasant day and
> | Cheers!
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> --
> http://dirk.eddelbuettel.com | @eddelbuettel | edd at debian.org