remove Boost

[dcooley]

Can replace all the date_to_string functions in Rcpp, for example something like

library(Rcpp)

cppFunction(
  
  code = '
    Rcpp::StringVector posixct_to_string( Rcpp::NumericVector nv ) {
      R_xlen_t i;
      R_xlen_t n = nv.size();
      
      Rcpp::StringVector sv( n );
      
      for( i = 0; i < n; ++i ) {
        Rcpp::Datetime d = nv[ i ];
        Rcpp::Rcout << d.getYear() << "-" << d.getMonth() << "-" << d.getDay() << "T" << d.getHours() << ":" << d.getMinutes() << ":" << d.getSeconds() << std::endl;
      }
      
      return sv;
    }
  '
)

[SymbolixAU]

some benchmarks

library(Rcpp)

cppFunction(
  code = "
    Rcpp::StringVector posixct_to_string( Rcpp::NumericVector nv ) {
      R_xlen_t i;
      R_xlen_t n = iv.size();
  
      Rcpp::StringVector sv( n );
      
      for( i = 0; i < n; ++i ) {
        Rcpp::Datetime d = iv[ i ];
        
        int yyyy = d.getYear();
        int mm = d.getMonth();
        int dd = d.getDay();
        int h = d.getHours();
        int m = d.getMinutes();
        int s = d.getSeconds();
        std::ostringstream os;
        os << std::setfill('0') << std::setw(4) << yyyy << '-';
        os << std::setfill('0') << std::setw(2) << mm << '-';
        os << std::setfill('0') << std::setw(2) << dd << 'T';
        os << std::setfill('0') << std::setw(2) << h << ':';
        os << std::setfill('0') << std::setw(2) << m << ':';
        os << std::setfill('0') << std::setw(2) << s;
          
        sv[i] = os.str();
      }
    return sv;
    }
  "
)

cppFunction(
  depends = "BH"
  , includes = '#include <boost/date_time.hpp>'
  , code = '
    Rcpp::StringVector bh_posix_to_string( Rcpp::NumericVector nv ) {
    
    R_xlen_t i;
    R_xlen_t n = nv.size();
    
    boost::local_time::tz_database tz_db;
    
    Rcpp::StringVector sv( n );
    
    for ( i = 0; i < n; ++i ) {
      Rcpp::Datetime d = nv[i];
      boost::gregorian::date dt( d.getYear(), d.getMonth(), d.getDay() );
      boost::posix_time::hours h( d.getHours() );
      boost::posix_time::minutes mins( d.getMinutes() );
      boost::posix_time::seconds sec( d.getSeconds() );
      boost::posix_time::time_duration td = h + mins + sec;
      
      boost::posix_time::ptime pt = boost::posix_time::ptime( dt, td );
      
      std::string s = boost::posix_time::to_iso_extended_string( pt );
      sv[i] = s.c_str();
    }
    return sv;
  }
  '
)


dte <- as.Date("2020-01-01")
date_to_string( dte )


psx <- as.POSIXct("2020-01-01 00:00:01")
posixct_to_string( psx )

vec <- rep(psx, 1e6)

rpp <- posixct_to_string( vec )
bh <- bh_posixct_to_string( vec )

all.equal( rpp, bh )

microbenchmark::microbenchmark(
  rcpp = {
    rpp <- posixct_to_string( vec )
  }
  , bh = {
    bh <- bh_posixct_to_string( vec )
  }, 
  times = 5
)

# Unit: milliseconds
# expr       min        lq      mean    median        uq       max neval
# rcpp  405.6936  413.4812  415.7236  416.2115  418.8226  425.8145    10
#   bh 1724.2650 1733.3073 1751.8593 1741.9584 1760.6240 1820.2224    10