Python provides two ways to import modules; we have already seen one:
>>> import math >>> print math <module 'math' (built-in)> >>> print math.pi 3.14159265359
If you import
math, you get a module object named
math. The module object contains constants like
pi and functions like
But if you try to access
pi directly, you get an error.
>>> print pi Traceback (most recent call last): File "<stdin>", line 1, in <module> NameError: name 'pi' is not defined
As an alternative, you can import an object from a module like this:
>>> from math import pi
Now you can access
pi directly, without dot notation.
>>> print pi 3.14159265359
Or you can use the star operator to import everything from the module:
>>> from math import * >>> cos(pi) -1.0
The advantage of importing everything from the math module is that your code can be more concise. The disadvantage is that there might be conflicts between names defined in different modules, or between a name from a module and one of your variables.