Hello,
this sounds like a newbie question, but I haven't been able to find a
good answer in Rcpp's documentation, source or testcases..
Say I have an internal data type which I want to wrap/unwrap as a DataFrame.
template<> SEXP wrap(const Foo &foo) {
Rcpp::DataFrame dataframe;
for (auto key : foo.keys()) {
if (key.is_numeric()) {
Rcpp::NumericVector vec;
// Fill vector with numbers
dataframe[ key ] = vec;
}
else if (key.is_string()) {
Rcpp::StringVector vec;
// Fill vector with strings
dataframe[ key ] = vec;
}
// etc
}
}
template<> Foo as(SEXP sexp) {
Rcpp::DataFrame dataframe(sexp);
// now what?
}
First, I need to iterate over all vectors in the dataframe. I could
access a vector using
dataframe["my_key"]
but that would require me to have a list of all the keys/column names
first. R has a colnames() function, but getting that into an
Rcpp::Function and calling it seems overly complicated..
I couldn't find anything in Rcpp's source or testcases.. but maybe
there's a simpler way?
Problem number two, how do I type the vector once I have it? The
dataframe can contain NumericVector or StringVector (or possibly
something different). Should I just construct each type, try/catch the
exceptions and see what fits, or is there a better way to determine the
type of a SEXP?
Thanks!
Christian
--
Christian Authmann
Philipps-Universität Marburg
Fachbereich Mathematik und Informatik
AG Datenbanksysteme
Hans-Meerwein-Straße
D-35032 Marburg
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