Rcpp 0.7.2
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Rcpp 0.7.2 is out, checkout Dirk’s blog for details
selected highlights from this new version:
character vectors
if one wants to mimic this R code in C
> x <- c( "foo", "bar" )one ends up with this :
SEXP x = PROTECT( allocVector( STRSXP, 2) ) ; SET_STRING_ELT( x, 0, mkChar( "foo" ) ) ; SET_STRING_ELT( x, 1, mkChar( "bar" ) ) ; UNPROTECT(1) ; return x ;
Rcpp lets you express the same like this :
CharacterVector x(2) ; x[0] = "foo" ; x[1] = "bar" ;
or like this if you have GCC 4.4 :
CharacterVector x = { "foo", "bar" } ;
environments, functions, ...
Now, we try to mimic this R code in C :rnorm( 10L, sd = 100 )You can do one of these two ways in Rcpp :
Environment stats("package:stats") ; Function rnorm = stats.get( "rnorm" ) ; return rnorm( 10, Named("sd", 100 ) ) ;
or :
Language call( "rnorm", 10, Named("sd", 100 ) ) ; return eval( call, R_GlobalEnv ) ;
and it will get better with the next release, where you will be able to just call call.eval()
and stats["rnorm"]
.
Using the regular R API, you'd write these liks this :
SEXP stats = PROTECT( R_FindNamespace( mkString("stats") ) ) ; SEXP rnorm = PROTECT( findVarInFrame( stats, install("rnorm") ) ) ; SEXP call = PROTECT( LCONS( rnorm, CONS(ScalarInteger(10), CONS(ScalarReal(100.0), R_NilValue)))) ; SET_TAG( CDDR(call), install("sd") ) ; SEXP res = PROTECT( eval( call, R_GlobalEnv ) ); UNPROTECT(4) ; return res ;
or :
SEXP call = PROTECT( LCONS( install("rnorm"), CONS(ScalarInteger(10), CONS(ScalarReal(100.0), R_NilValue)))) ; SET_TAG( CDDR(call), install("sd") ) ; SEXP res = PROTECT( eval( call, R_GlobalEnv ) ); UNPROTECT(2) ; return res ;
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