Numpy vectorization messes up data type (2)

Question

I\'m having unwanted behaviour come out of np.vectorize, namely, it changes the datatype of the argument going into the original function. My original question

Answer 1

Just as in the original question, I can "solve" the problem by forcing the incoming argument to be a pandas datetime object, by adding dt = pd.to_datetime(dt) before the first if-statement of the function.

To be honest, this feels like patching-up something that's broken and should not be used. I'll just use .apply instead and take the performance hit. Anyone that feels there's a better solution is very much invited to share :)