I am a beginner in python. I have this matrix:

```
    Mat RX = (Mat_<double>(4, 4) <<
          1, 0,         0,          0,
          0, cos(roll), -sin(roll), 0,
          0, sin(roll), cos(roll),  0,
          0, 0,         0,          1);

```

How do I make this in python? It gives error when I try something like this:

```
    MatrixX = np.mat('1,2,3;cos(roll),6,7')

```