which_max.h

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// -*- mode: C++; c-indent-level: 4; c-basic-offset: 4; tab-width: 8 -*-
//
// which_max.h: Rcpp R/C++ interface class library -- which.max
//
// Copyright (C) 2012   Dirk Eddelbuettel and Romain Francois
//
// This file is part of Rcpp.
//
// Rcpp is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 2 of the License, or
// (at your option) any later version.
//
// Rcpp is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Rcpp.  If not, see <http://www.gnu.org/licenses/>.
 
#ifndef Rcpp__sugar__which_max_h
#define Rcpp__sugar__which_max_h
 
namespace Rcpp{
namespace sugar{
 
template <int RTYPE, bool NA, typename T>
class WhichMax {
public:
    typedef typename Rcpp::VectorBase<RTYPE,NA,T> VEC_TYPE ;
    typedef typename Rcpp::traits::storage_type<RTYPE>::type STORAGE ;
        WhichMax(const VEC_TYPE& obj_ ) : obj(obj_){}
 
        R_xlen_t get() const {
            STORAGE current = obj[0] ;
            STORAGE min = current ;
            R_xlen_t index = 0 ;
            if( Rcpp::traits::is_na<RTYPE>(current) ) return NA_INTEGER ;
            R_xlen_t n = obj.size() ;
            for( R_xlen_t i=1; i<n; i++){
                    current = obj[i] ;
                    if( Rcpp::traits::is_na<RTYPE>(current) ) return NA_INTEGER ;
                    if( current > min ){
                        min = current ;
                        index = i ;
                    }
                }
                return index ;
        }
 
private:
    const VEC_TYPE& obj ;
 
} ;
 
template <int RTYPE, typename T>
class WhichMax<RTYPE,false,T> {
public:
    typedef typename Rcpp::VectorBase<RTYPE,false,T> VEC_TYPE ;
    typedef typename Rcpp::traits::storage_type<RTYPE>::type STORAGE ;
        WhichMax(const VEC_TYPE& obj_ ) : obj(obj_){}
 
        R_xlen_t get() const {
            STORAGE current = obj[0] ;
            STORAGE min = current ;
            R_xlen_t index = 0 ;
            R_xlen_t n = obj.size() ;
            for( R_xlen_t i=1; i<n; i++){
                    current = obj[i] ;
                    if( current > min ){
                        min = current ;
                        index = i ;
                    }
                }
                return index ;
        }
 
private:
    const VEC_TYPE& obj ;
 
} ;
 
 
} // sugar
 
 
 
template <int RTYPE, bool NA, typename T>
R_xlen_t which_max( const VectorBase<RTYPE,NA,T>& t ){
        return sugar::WhichMax<RTYPE,NA,T>(t).get() ;
}
 
} // Rcpp
#endif