TypeError: __array_prepare__ must return an ndarray or subclass thereof which is otherwise identical to its input

This error message typically occurs when working with numpy arrays and indicates that the __array_prepare__ method is not returning an object of the expected type.

The __array_prepare__ method is part of the numpy array protocol and is used to prepare an array for a computation. It is called before any computation is performed on the array and allows the array to be modified or validated before use.

To fix this error, you should ensure that your implementation of __array_prepare__ returns an ndarray or subclass thereof that is identical to the input array. You may also want to check that the input array is of the expected type and shape before performing any computations.

Here is an example implementation of __array_prepare__ that simply returns the input array:

class MyClass(np.ndarray):
    def __array_prepare__(self, obj, context=None):
        return obj

In this case, the method simply returns the input array unchanged, but you could modify or validate the array as needed before returning it.