Feature/issue383 -- closes #383

[eddelbuettel]

this should close #383:

• works on square and non-square integer and real matrices
• deals with dimnames
• will add one for strings as well, not sure I can be bothered for complex

[eddelbuettel]

Bump to @jjallaire @kevinushey -- please take a look when time permits.

This is an addition of three free functions (along with tests), and changes no interface.

[jjallaire]

LGTM however I don't know enough about the internals to fully provide the green light. @kevinushey ?

[kevinushey]

You could do something like this:

SEXP oldDimNames = Rf_getAttrib(x, R_DimNamesSymbol);
if (!Rf_isNull(oldDimNames)) {
    Shield<SEXP> newDimNames(Rf_allocVector(VECSXP, 2));
    SET_VECTOR_ELT(newDimNames, 0, VECTOR_ELT(oldDimNames, 1));
    SET_VECTOR_ELT(newDimNames, 1, VECTOR_ELT(oldDimNames, 0));
    Rf_setAttrib(r, R_DimNamesSymbol, newDimNames);
}

Marginally cleaner?

[eddelbuettel]

Nice. Anything that avoid PROTECT and UNPROTECT has my vote :)

[eddelbuettel]

That's been committed.

[kevinushey]

This is fine as-is but made some comments that might help clean up (code duplication, Shield<SEXP>)

[eddelbuettel]

Very helpful -- thanks for he comments, Kevin. Will revise once more.

[eddelbuettel]

Bump. @kevinushey if you can take another quick look...

[kevinushey]

Looks good to me!