On 19 May 2011 at 15:27, Jason Lessels wrote:
| Hi Dirk,
| Thanks for your help. I am 99% confident that there is a better method to my
example below, but this is the only way i was able to pass the format string to
for the datetime object.
|
| src<-'
| StringVector stringVec(dates);
| int n_stringVec=stringVec.size();
| std::string fmt =Rcpp::as<std::string>( format );
|
| DatetimeVector dateAll(n_stringVec);
|
| std::string input;
|
| for(int i=0;i<n_stringVec;i++){
| input = stringVec[i];
| Datetime dateTemp(input,fmt);
| dateAll[i] = dateTemp;
| }
|
| return wrap(dateAll);
| '
| library(inline)
|
cpp_DatetimeVector<-cxxfunction(signature(dates="string",format="string"),src,plugin="Rcpp")
|
| ####Create a fictional dataset
| foo<-seq(as.POSIXct("1960-01-01 00:00:00"),as.POSIXct("2010-01-01
00:00:00"),by='hour')
|
| system.time(test<-cpp_DatetimeVector(foo,"%Y-%m-%d %H:%M:%OS"))
| # user system elapsed
| # 98.607 0.904 101.061
| system.time(test2<-strptime(foo,"%Y-%m-%d %H:%M:%OS"))
| # user system elapsed
| # 14.089 0.261 14.501
I see. Yes, the 101.061 is unappealing. But dealing with timezones etc is
also very frustrating. What I would is
test2 <- strptime(foo,"%Y-%m-%d %H:%M:%OS") ## you now have POSIXct
cpp_DatetimeVector( as.numeric(test2) ) ## pass POSIXct down as
numeric
with a rewritten cpp_DatetimeVector which does just
src<-'
DatetimeVector datevec(numericdates); ## numericdates is
as.numeric(POSIXct)
// do stuff then return .....
'
which should be very quick to execute.
In the uses I had, time always was (fractional) seconds since the epoch so I
never wrote another constructor....
Hope this helps, Dirk
--
Gauss once played himself in a zero-sum game and won $50.
-- #11 at http://www.gaussfacts.com
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