title: Python from X Import Y
If you have read the
import statements wiki then you’d have seen me use this statement in one of the examples. Today, we’ll try to understand what it does
So picking up the same example:
>>> from math import ceil, sqrt >>> # here it would be >>> sqrt(36) <<< 6
Or we could use this:
>>> import math >>> # here it would be >>> math.sqrt(36) <<< 6
Then our code would look like
math.sqrt(x) instead of
sqrt(x). This happens because when we use
import x, a namespace
x is itself created to avoid name conflicts. You have to access every single object of the module as
x.<name>. But when we use
from x import y we agree to add
y to the main global namespace. So while using this we have to make sure that we don’t have an object with same name in our program.
from x import yif an object named
For example, in
os module there’s a method
open. But we even have a built-in function called
open. So, here we should avoid using
from os import open.
We can even use
form x import *, this would import all the methods, classes of that module to the global namespace of the program. This is a bad programming practice. Please avoid it.
In general you should avoid
from x import y simply because of the problems it may cause in large scale programs. For example, you never know if a fellow programmer might want to make a new function that happens to be the name of one of the existing functions. You also do not know whether Python will change the library that you are importing functions from. While these problems won’t exist as often for solo projects, as stated before, it is bad programming practice and should be avoided.
You may use
from x import y as z, this would import
x module as
z . Using
as you can rename the method imported according to your wish. At times, the method name may be too large to spell again and again. By using
as, you can rename it as you wish. For example,
from matplotlib import pyplot as plt – here
pyplot has been renamed to
plt and can be used normally.