Eigen::Reshaped< XprType, Rows, Cols, Order > Class Template Reference

Expression of a fixed-size or dynamic-size reshape. More...

Inheritance diagram for Eigen::Reshaped< XprType, Rows, Cols, Order >:

Public Types
typedef Impl	Base

Public Member Functions
	Reshaped (XprType &xpr)
	Reshaped (XprType &xpr, Index reshapeRows, Index reshapeCols)

Private Types
typedef ReshapedImpl< XprType, Rows, Cols, Order, typename internal::traits< XprType >::StorageKind >	Impl

Detailed Description

template<typename XprType, int Rows, int Cols, int Order>
class Eigen::Reshaped< XprType, Rows, Cols, Order >

Expression of a fixed-size or dynamic-size reshape.

Template Parameters

XprType	the type of the expression in which we are taking a reshape
Rows	the number of rows of the reshape we are taking at compile time (optional)
Cols	the number of columns of the reshape we are taking at compile time (optional)
Order	can be ColMajor or RowMajor, default is ColMajor.

This class represents an expression of either a fixed-size or dynamic-size reshape. It is the return type of DenseBase::reshaped(NRowsType,NColsType) and most of the time this is the only way it is used.

If you want to directly manipulate reshaped expressions, for instance if you want to write a function returning such an expression, it is advised to use the auto keyword for such use cases.

Here is an example illustrating the dynamic case:

#include <Eigen/Core>
#include <iostream>
 
template<typename Derived>
const Eigen::Reshaped<const Derived>
reshape_helper(const Eigen::MatrixBase<Derived>& m, int rows, int cols)
{
  return Eigen::Reshaped<const Derived>(m.derived(), rows, cols);
}
 
int main(int, char**)
{
  Eigen::MatrixXd m(3, 4);
  m << 1, 4, 7, 10,
       2, 5, 8, 11,
       3, 6, 9, 12;
  std::cout << m << std::endl;
  Eigen::Ref<const Eigen::MatrixXd> n = reshape_helper(m, 2, 6);
  std::cout << "Matrix m is:" << std::endl << m << std::endl;
  std::cout << "Matrix n is:" << std::endl << n << std::endl;
}

Output:

 1  4  7 10
 2  5  8 11
 3  6  9 12
Matrix m is:
 1  4  7 10
 2  5  8 11
 3  6  9 12
Matrix n is:
 1  3  5  7  9 11
 2  4  6  8 10 12

Here is an example illustrating the fixed-size case:

#include <Eigen/Core>
#include <iostream>
 
template<typename Derived>
Eigen::Reshaped<Derived, 4, 2>
reshape_helper(Eigen::MatrixBase<Derived>& m)
{
  return Eigen::Reshaped<Derived, 4, 2>(m.derived());
}
 
int main(int, char**)
{
  Eigen::MatrixXd m(2, 4);
  m << 1, 2, 3, 4,
       5, 6, 7, 8;
  Eigen::MatrixXd n = reshape_helper(m);
  std::cout << "matrix m is:" << std::endl << m << std::endl;
  std::cout << "matrix n is:" << std::endl << n << std::endl;
  return 0;
}

Output:

matrix m is:
1 2 3 4
5 6 7 8
matrix n is:
1 3
5 7
2 4
6 8

See also

DenseBase::reshaped(NRowsType,NColsType)

Definition at line 97 of file Reshaped.h.

Member Typedef Documentation

Base

template<typename XprType , int Rows, int Cols, int Order>

typedef Impl Eigen::Reshaped< XprType, Rows, Cols, Order >::Base

Definition at line 103 of file Reshaped.h.

Impl

template<typename XprType , int Rows, int Cols, int Order>

typedef ReshapedImpl<XprType, Rows, Cols, Order, typename internal::traits<XprType>::StorageKind> Eigen::Reshaped< XprType, Rows, Cols, Order >::Impl

private

Definition at line 100 of file Reshaped.h.

Constructor & Destructor Documentation

Reshaped() [1/2]

template<typename XprType , int Rows, int Cols, int Order>

Eigen::Reshaped< XprType, Rows, Cols, Order >::Reshaped ( XprType &  xpr )

inline

Fixed-size constructor

Definition at line 110 of file Reshaped.h.

      : Impl(xpr)
    {
      EIGEN_STATIC_ASSERT(RowsAtCompileTime!=Dynamic && ColsAtCompileTime!=Dynamic,THIS_METHOD_IS_ONLY_FOR_FIXED_SIZE)
      eigen_assert(Rows * Cols == xpr.rows() * xpr.cols());
    }

Reshaped() [2/2]

template<typename XprType , int Rows, int Cols, int Order>

Eigen::Reshaped< XprType, Rows, Cols, Order >::Reshaped ( XprType &  xpr, Index  reshapeRows, Index  reshapeCols  )

inline

Dynamic-size constructor

Definition at line 120 of file Reshaped.h.

      : Impl(xpr, reshapeRows, reshapeCols)
    {
      eigen_assert((RowsAtCompileTime==Dynamic || RowsAtCompileTime==reshapeRows)
          && (ColsAtCompileTime==Dynamic || ColsAtCompileTime==reshapeCols));
      eigen_assert(reshapeRows * reshapeCols == xpr.rows() * xpr.cols());
    }

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The documentation for this class was generated from the following file:

• Reshaped.h