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

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)

Inherits Eigen::ReshapedImpl< XprType, Rows, Cols, Order, internal::traits< XprType >::StorageKind >.

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

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

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

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

• Reshaped.h