参考

官网教程

Reshape

• 用法：DenseBase::reshaped(NRowsType,NColsType)
• 默认按照列优先进行元素重排；
• 通过RowMajor设置按照行优先；
• 通过AutoOrder设置按照存储顺序重排；
• PlainObjectBase::resize(Index,Index)也可以实现重排；

void demo_26()
{Matrix4i m = Matrix4i::Random();m = m - m / 10 * 10;cout << "Here is the matrix a:" << endl << m << endl;cout << "Here is m.reshaped(2, 8):" << endl << m.reshaped(2, 8) << endl;cout << "Here is m.reshaped().transpose():" << endl << m.reshaped().transpose() << endl;cout << "Here is m.reshaped<RowMajor>().transpose():  " << endl << m.reshaped<RowMajor>().transpose() << endl;m.resize(2,8);cout << "Here is the matrix m after m.resize(2,8):" << endl << m << endl;Matrix<int,Dynamic,Dynamic,RowMajor> n = Matrix4i::Random();n = n - n / 10 * 10;cout << "Here is the matrix n:" << endl << n << endl;cout << "Here is n.reshaped(2, 8):" << endl << n.reshaped(2, 8) << endl;cout << "Here is n.reshaped<AutoOrder>(2, 8):" << endl << n.reshaped<AutoOrder>(2, 8) << endl;n.resize(2,8);cout << "Here is the matrix n after n.resize(2,8):" << endl << n << endl;}

输出

build$ ./eigenTest 
Here is the matrix a:9  9 -5 -4
-8 -9  7  53 -8 -2  91  8  3  2
Here is m.reshaped(2, 8):9  3  9 -8 -5 -2 -4  9
-8  1 -9  8  7  3  5  2
Here is m.reshaped().transpose():9 -8  3  1  9 -9 -8  8 -5  7 -2  3 -4  5  9  2
Here is m.reshaped<RowMajor>().transpose():  9  9 -5 -4 -8 -9  7  5  3 -8 -2  9  1  8  3  2
Here is the matrix m after m.resize(2,8):9  9 -5 -4
-8 -9  7  53 -8 -2  91  8  3  2
Here is the matrix n:6  2 -2  2
-3 -6 -7  5
-2 -4 -2 -13 -9  5  8
Here is n.reshaped(2, 8):6 -2  2 -4 -2 -2  2 -1
-3  3 -6 -9 -7  5  5  8
Here is n.reshaped<AutoOrder>(2, 8):6  2 -2  2 -3 -6 -7  5
-2 -4 -2 -1  3 -9  5  8
Here is the matrix n after n.resize(2,8):6  2 -2  2 -3 -6 -7  5
-2 -4 -2 -1  3 -9  5  8