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Basics Of Python Modules

  • Last Updated : 24 Jan, 2022

A library refers to a collection of modules that together cater to a specific type of needs or application. Module is a file(.py file) containing variables, class definitions statements, and functions related to a particular task. Python modules that come preloaded with Python are called standard library modules. 

Creating our module

We will be creating a module named that converts values from F to C and vice-versa.


# to convert between
# between Fahrenheit and Centigrade
# function to convert F to C
def to_centigrade(x):
      return 5 * (x - 32) / 9.0
# function to convert C to F
def to_fahrenheit(x):
       return 9 * x / 5.0 + 32
# constants
# water freezing temperature(in Celsius)
# water freezing temperature(in Fahrenheit)    
FREEZING_F = 32.0     

Now save this python file and the module is created. This module can be used in other programs after importing it.

Importing a module

In python, in order to use a module, it has to be imported. Python provides multiple ways to import modules in a program : 

  1. To import the entire module : 
import module_name
  1. To import only a certain portion of the module : 
from module_name import object_name
  1. To import all the objects of the module : 
from module_name import *


Using an imported module

After importing the module, we can use any function/definition of the imported module as per the following syntax: 


This way of referring to the module‚Äôs object is called dot notation. 
If we import a function using from, there is no need to mention the module name and the dot notation to use that function.
Example 1 : Importing the whole module : 


# importing the module
import tempConversion
# using a function of the module
# fetching an object of the module

Output : 


Example 2 : Importing particular components of the module : 


# importing the to_fahrenheit() method
from tempConversion import to_fahrenheit
# using the imported method
# importing the FREEZING_C object
from tempConversion import FREEZING_C
# printing the imported variable

Output : 



Python standard library functions

The python interpreter has a number of functions built into it that are always available. To use these built-in functions of python directly call the functions, like function_name(). Some built-in library functions are : input(), int(), float() etc


num = 5
print("Number entered = ", num)
# oct() converts to octal number-string
onum = oct(num)  
# hex() converts to hexadecimal number-string    
hnum = hex(num)    
print("Octal conversion yields", onum)
print("Hexadecimal conversion yields", hnum)

Output : 

Number entered = 5
Octal conversion yields 0o5
Hexadecimal conversion yields 0x5


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