Hi Jason,
On 19 May 2011 at 11:00, Jason Lessels wrote:
| Hi,
| I have a very limited understanding of the class definition, but i was
wondering if I could make a request for a minor change in relation to the two
classes Datetime and the extension DatetimeVector. I have been successfully
using Datetime class, passing both the date string and the format string, as
this is allowed with the following definition;
|
| 00047 Datetime::Datetime(const std::string &s, const std::string &fmt) {
| 00048 Rcpp::Function strptime("strptime"); // we cheat and
call strptime() from R
| 00049 Rcpp::Function asPOSIXct("as.POSIXct"); // and we need
to convert to POSIXct
| 00050 m_dt = Rcpp::as<double>(asPOSIXct(strptime(s, fmt)));
| 00051 update_tm();
| 00052 }
|
| however the DatetimeVector definition uses;
|
| 00027 DatetimeVector::DatetimeVector(SEXP vec)
throw(std::range_error) : v() {
| 00028 int i;
| 00029 if (!Rf_isNumeric(vec) || Rf_isMatrix(vec) ||
Rf_isLogical(vec))
| 00030 throw std::range_error("DatetimeVector: invalid
numeric vector in constructor");
| 00031 int len = Rf_length(vec);
| 00032 if (len == 0)
| 00033 throw std::range_error("DatetimeVector: null
vector in constructor");
| 00034 v.resize(len);
| 00035 for (i = 0; i < len; i++)
| 00036 v[i] = Datetime(
static_cast<double>(REAL(vec)[i]));
| 00037 }
|
|
| where line 36 calls Datetime without the ability to provide the format. Would
it be possible for this to be changed to allow the format of the Datetime
string. Currently I have to either convert the date string in R, or use an
additional loop to convert the format, which make this slower than using the
standard methods in R.
|
| Sorry in advance if my understanding is incorrect.
I fear you may be confused. To see what constructors are defined, see the
corresponding class declaration in its header. For Datetime we get
[...]
class Datetime {
public:
Datetime();
Datetime(SEXP s);
Datetime(const double &dt); // from double, just like
POSIXct
Datetime(const std::string &s, const std::string &fmt="%Y-%m-%d
%H:%M:%OS");
Datetime(const Datetime ©);
[...]
implying that we can construct 'empty', from SEXP, from double, from string +
string and lastly from an existing Datetime.
Also, your second code quote is 'an existance proof' of the asked-for
constructor: Had it now existed, the second quote would not have compiled.
As for your performance issues: can you send a small mock-up example we can
grind through benchmark() or other timing tools?
Dirk
--
Gauss once played himself in a zero-sum game and won $50.
-- #11 at http://www.gaussfacts.com
_______________________________________________
Rcpp-devel mailing list
Rcpp-devel@lists.r-forge.r-project.org
https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
