Hello everyone!
I find the reflection about y-axis, and this is my result: A_reflection_yaxis = np.array([[-2,3],[-2,1]]). Is this correct?

I have as a result of eigenvalues and eigenvectors of matrix A_reflection_yaxis something strange:
(array([-0.5+1.93649167j, -0.5-1.93649167j]), array([[ 0.77459667+0.j , 0.77459667-0.j ],
[-0.38729833-0.5j, -0.38729833+0.5j]])).
And function plot_transformation can’t visualize this result. Please, help me to find the solution.

Your eigenvalues and eigenvectors of A_reflection_yaxis is correct, but your A_reflection_yaxis is wrong, Thats why plot_transformation can’t visualize.

First fix your A_reflection_yaxis then your code will work fine,

FYI: Reflection about y-axis (the vertical axis) means
negate the value of the x-coordinate of each point, but leave the y-coordinate value the same
Example: point (5,4) will become (-5,4)