Firstly, I implemented this effect using Python Node .
But I want to use 'pythonexprs' instead of script in the transformer node.
So I modified the code.
He is still able to calculate the minimum Y-axis value of the point in the model.
But when I joined pythonexprs, he reported an error.
I cannot solve it and need the help of experts. My English is poor. If I say something wrong, I'm sorry.