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muSpectre/src/common/field_map.hh
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field_map.hh
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/**
* @file field_map.hh
*
* @author Till Junge <till.junge@epfl.ch>
*
* @date 26 Sep 2017
*
* @brief just and indirection to include all iterables defined for fields
*
* Copyright © 2017 Till Junge
*
* µSpectre 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 3, or (at
* your option) any later version.
*
* µSpectre 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 µSpectre; see the file COPYING. If not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include "common/field_map_tensor.hh"
#include "common/field_map_matrixlike.hh"
#include "common/field_map_scalar.hh"
#include <sstream>
#include <stdexcept>
#include <type_traits>
#ifndef FIELD_MAP_H
#define FIELD_MAP_H
namespace muSpectre {
/**
* allows to iterate over raw data as if it were a FieldMap. This is
* particularly useful when interacting with external solvers, such
* as scipy and Eigen
* @param EigenMap needs to be statically sized a Eigen::Map<XXX>
*
* @warning This type is not safe for re-use. I.e., after there has
* been an assignment to the underlying eigen array, the
* `RawFieldMap` might be invalidated!
*/
template <class EigenMap>
class RawFieldMap
{
public:
/**
* determining the constness of the mapped array required in order
* to formulate the constructors const-correctly
*/
constexpr static bool IsConst{
std::is_const<
std::remove_pointer_t<typename EigenMap::PointerArgType>>::value};
//! short-hand for the basic scalar type
using T = typename EigenMap::Scalar;
//! raw pointer type to store
using T_ptr = std::conditional_t<IsConst,
const T*,
T*>;
//! input array (~field) type to be mapped
using FieldVec_t = std::conditional_t<IsConst,
const Eigen::VectorXd,
Eigen::VectorXd>;
//! Plain mapped Eigen type
using EigenPlain = typename EigenMap::PlainObject;
//! Default constructor
RawFieldMap() = delete;
//! constructor from a *contiguous* array
RawFieldMap(Eigen::Map<FieldVec_t> vec,
Dim_t nb_rows=EigenMap::RowsAtCompileTime,
Dim_t nb_cols=EigenMap::ColsAtCompileTime):
data{vec.data()},
nb_rows{nb_rows},
nb_cols{nb_cols},
nb_components{nb_rows * nb_cols},
nb_pixels(vec.size()/nb_components)
{
if ((nb_rows == Eigen::Dynamic) or
(nb_cols == Eigen::Dynamic)) {
throw FieldError
("You have to specify the number of rows and columns if you map a "
"dynamically sized Eigen Map type.");
}
if ((nb_rows < 1) or (nb_cols < 1)) {
throw FieldError("Only positive numbers of rows and columns make "
"sense");
}
if (vec.size() % this->nb_components != 0) {
std::stringstream err{};
err << "The vector size of " << vec.size()
<< " is not an integer multiple of the size of value_type, which "
<< "is " << this->nb_components << ".";
throw std::runtime_error(err.str());
}
}
//! constructor from a *contiguous* array
RawFieldMap(Eigen::Ref<FieldVec_t> vec,
Dim_t nb_rows=EigenMap::RowsAtCompileTime,
Dim_t nb_cols=EigenMap::ColsAtCompileTime):
data{vec.data()},
nb_rows{nb_rows},
nb_cols{nb_cols},
nb_components{nb_rows * nb_cols},
nb_pixels(vec.size()/nb_components)
{
if (vec.size() % this->nb_components != 0) {
std::stringstream err{};
err << "The vector size of " << vec.size()
<< " is not an integer multiple of the size of value_type, which "
<< "is " << this->nb_components << ".";
throw std::runtime_error(err.str());
}
}
//! Copy constructor
RawFieldMap(const RawFieldMap &other) = delete;
//! Move constructor
RawFieldMap(RawFieldMap &&other) = default;
//! Destructor
virtual ~RawFieldMap() = default;
//! Copy assignment operator
RawFieldMap& operator=(const RawFieldMap &other) = delete;
//! Move assignment operator
RawFieldMap& operator=(RawFieldMap &&other) = delete;
//! returns number of EigenMaps stored within the array
size_t size() const {return this->nb_pixels;}
//! forward declaration of iterator type
template <bool IsConst>
class iterator_t;
using iterator = iterator_t<false>;
using const_iterator = iterator_t<true>;
//! returns an iterator to the first element
iterator begin() { return iterator{*this, 0};}
const_iterator begin() const {
return const_iterator{*this, 0};}
//! returns an iterator past the last element
iterator end() {return iterator{*this, this->size()};}
const_iterator end() const {
return const_iterator{*this, this->size()};}
//! evaluates the average of the field
EigenPlain mean () const {
using T_t = EigenPlain;
T_t mean(T_t::Zero(this->nb_rows, this->nb_cols));
for (auto && val: *this) {
mean += val;
}
mean /= this->size();
return mean;
}
protected:
inline T_ptr get_data() {return data;}
inline const T_ptr get_data() const {return data;}
//! raw data pointer (ugly, I know)
T_ptr data;
const Dim_t nb_rows;
const Dim_t nb_cols;
const Dim_t nb_components;
//! number of EigenMaps stored within the array
size_t nb_pixels;
private:
};
/**
* Small iterator class to be used with the RawFieldMap
*/
template <class EigenMap>
template <bool IsConst>
class RawFieldMap<EigenMap>::iterator_t
{
public:
//! short hand for the raw field map's type
using Parent = RawFieldMap<EigenMap>;
//! the map needs to be friend in order to access the protected constructor
friend Parent;
//! stl compliance
using value_type = std::conditional_t
<IsConst,
Eigen::Map<const typename EigenMap::PlainObject>,
EigenMap>;
using T_ptr = std::conditional_t<IsConst,
const Parent::T_ptr,
Parent::T_ptr>;
//! stl compliance
using iterator_category = std::forward_iterator_tag;
//! Default constructor
iterator_t() = delete;
//! Copy constructor
iterator_t(const iterator_t &other) = default;
//! Move constructor
iterator_t(iterator_t &&other) = default;
//! Destructor
virtual ~iterator_t() = default;
//! Copy assignment operator
iterator_t& operator=(const iterator_t &other) = default;
//! Move assignment operator
iterator_t& operator=(iterator_t &&other) = default;
//! pre-increment
inline iterator_t & operator++() {
++this->index;
return *this;
}
//! dereference
inline value_type operator *() {
return value_type(raw_ptr + this->map.nb_components*index,
this->map.nb_rows, this->map.nb_cols);
}
//! inequality
inline bool operator != (const iterator_t & other) const {
return this->index != other.index;
}
//! equality
inline bool operator == (const iterator_t & other) const {
return this->index == other.index;
}
protected:
//! protected constructor
iterator_t (const Parent& map,
size_t start):
raw_ptr{map.get_data()}, map{map}, index{start} { }
template <bool dummy_non_const = not IsConst>
iterator_t (std::enable_if_t<dummy_non_const, Parent&> map,
size_t start):
raw_ptr{map.data}, map{map}, index{start} {
static_assert(dummy_non_const == not IsConst, "SFINAE");}
//! raw data
T_ptr raw_ptr;
//! ref to underlying map
const Parent & map;
//! currently pointed-to element
size_t index;
private:
};
} // muSpectre
#endif /* FIELD_MAP_H */
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