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// -*- mode: C++; c-indent-level: 4; c-basic-offset: 4; tab-width: 4 -*-
//
// diff.h: Rcpp R/C++ interface class library -- diff
//
// Copyright (C) 2010 - 2013 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__diff_h
#define Rcpp__sugar__diff_h
namespace Rcpp{
namespace sugar{
// NOTE: caching the previous value so that we only have to fetch the
// value once only works because we process the object from left to
// right
template <int RTYPE, bool LHS_NA, typename LHS_T>
class Diff : public Rcpp::VectorBase< RTYPE, LHS_NA , Diff<RTYPE,LHS_NA,LHS_T> > {
public:
typedef typename Rcpp::VectorBase<RTYPE,LHS_NA,LHS_T> LHS_TYPE ;
typedef typename Rcpp::traits::storage_type<RTYPE>::type STORAGE ;
Diff( const LHS_TYPE& lhs_ ) :
lhs(lhs_),
previous(lhs_[0]),
previous_index(0),
was_na(traits::is_na<RTYPE>(previous))
{}
inline STORAGE operator[]( R_xlen_t i ) const {
STORAGE y = lhs[i+1] ;
if( previous_index != i ){
// we don't know the previous value, we need to get it.
set_previous(i, lhs[i] ) ; // record the current value
}
if( was_na || traits::is_na<RTYPE>(y) ) {
set_previous(i+1, y ) ;
return traits::get_na<RTYPE>() ; // NA
}
STORAGE res = y - previous ;
set_previous( i+1, y) ;
return res ;
}
inline void set_previous(R_xlen_t i, STORAGE value) const {
previous = value ;
was_na = traits::is_na<RTYPE>(previous) ;
previous_index = i ;
}
inline R_xlen_t size() const { return lhs.size() - 1 ; }
private:
const LHS_TYPE& lhs ;
mutable STORAGE previous ;
mutable R_xlen_t previous_index ;
mutable bool was_na ;
} ;
template <typename LHS_T, bool LHS_NA>
class Diff<REALSXP, LHS_NA, LHS_T> : public Rcpp::VectorBase< REALSXP, LHS_NA, Diff<REALSXP,LHS_NA,LHS_T> >{
public:
typedef typename Rcpp::VectorBase<REALSXP,LHS_NA,LHS_T> LHS_TYPE ;
Diff( const LHS_TYPE& lhs_ ) : lhs(lhs_), previous(lhs_[0]), previous_index(0) {}
inline double operator[]( R_xlen_t i ) const {
double y = lhs[i+1] ;
if( previous_index != i ) previous = lhs[i] ;
double res = y - previous ;
previous = y ;
previous_index = i+1 ;
return res ;
}
inline R_xlen_t size() const { return lhs.size() - 1 ; }
private:
const LHS_TYPE& lhs ;
mutable double previous ;
mutable R_xlen_t previous_index ;
} ;
template <int RTYPE, typename LHS_T>
class Diff<RTYPE,false,LHS_T> : public Rcpp::VectorBase< RTYPE, false , Diff<RTYPE,false,LHS_T> > {
public:
typedef typename Rcpp::VectorBase<RTYPE,false,LHS_T> LHS_TYPE ;
typedef typename Rcpp::traits::storage_type<RTYPE>::type STORAGE ;
Diff( const LHS_TYPE& lhs_ ) : lhs(lhs_), previous(lhs[0]), previous_index(0) {}
inline STORAGE operator[]( R_xlen_t i ) const {
STORAGE y = lhs[i+1] ;
if( previous_index != i ) previous = lhs[i] ;
STORAGE diff = y - previous ;
previous = y ;
previous_index = i+1 ;
return y - previous ;
}
inline R_xlen_t size() const { return lhs.size() - 1 ; }
private:
const LHS_TYPE& lhs ;
mutable STORAGE previous ;
mutable R_xlen_t previous_index ;
} ;
} // sugar
template <bool LHS_NA, typename LHS_T>
inline sugar::Diff<INTSXP,LHS_NA,LHS_T> diff(
const VectorBase<INTSXP,LHS_NA,LHS_T>& lhs
){
return sugar::Diff<INTSXP,LHS_NA,LHS_T>( lhs ) ;
}
template <bool LHS_NA, typename LHS_T>
inline sugar::Diff<REALSXP,LHS_NA,LHS_T> diff(
const VectorBase<REALSXP,LHS_NA,LHS_T>& lhs
){
return sugar::Diff<REALSXP,LHS_NA,LHS_T>( lhs ) ;
}
} // Rcpp
#endif
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