Difference between import numpy and import numpy as np

Question

I understand that when possible one should use

import numpy as np

This helps keep away any conflict due to namespaces. But I have noticed that

Answer 1

This is a language feature. f2py is a subpackage of the module numpy and must be loaded separately.

This feature allows:

• you to load from numpy only the packages you need, speeding up execution.
• the developers of f2py to have namespace separation from the developers of another subpackage.

Notice however that import numpy.f2py or its variant import numpy.f2py as myf2py are still loading the parent module numpy.

Said that, when you run

import numpy as np
np.f2py

You receive an AttributeError because f2py is not an attribute of numpy, because the __init__() of the package numpy did not declare in its scope anything about the subpackage f2py.