If you're in and using python for science (which it seems you are) part of that will be learning and understanding scientific libraries, for me these would be
knowing how to use the right libraries and vectorize your code is essential for scientific computing.
I wanted to add that, handling large numeric datasets in common pythonic ways(object oriented approaches, lists, iterators) can be extremely inefficient. In scientific computing, it can be necessary to structure your code in ways that differ drastically from how most conventional python coders approach data.