Python Modules

Python Language Modules

1) What is Python Module?
2) Purpose of Modules
3) Types of Modules
4) How to use Modules
5) User defined Modules in Python

1) What is Python Module?

> A module is a file consisting of Python code. It can define functions, classes, and variables, and can also include runnable code. Any Python file can be referenced as a module.

> A file containing Python code, for example: test.py, is called a module, and its name would be test..

Module vs. Function

Function: it’s a block of code that you can use/reuse by calling it with a keyword. Eg. print() is a function.

Module: it’s a .py file that contains a list of functions (it can also contain variables and classes). Eg. in statistics.mean(a), mean is a function that is found in the statistics module.

2) Purpose of Modules

> As our program grows more in the size we may want to split it into several files for easier maintenance as well as re-usability of the code. The solution to this is Modules.

> We can define your most used functions in a module and import it, instead of copying their definitions into different programs. A module can be imported by another program to make use of its functionality. This is how you can use the Python standard library as well.

3) Types of Modules

> Python provides us with some built-in modules, which can be imported by using the “import” keyword.

> Python also allows us to create your own modules and use them in your programs.

4) How to use Modules

Built-in modules are written in C and integrated with the Python interpreter.

Each built-in module contains resources for certain system-specific functionalities such as OS management, disk IO, etc.

>>> help(‘modules’)

There is a Python Standard Library with dozens of built-in modules. From those, five important modules,

random, statistics, math, datetime, csv

Python math module,

This contains factorial, power, and logarithmic functions, but also some trigonometry and constants.

i) import math

And then:

math.factorial(5)
math.pi
math.sqrt(5)
math.log(256, 2)

ii) import math as m

And then:

m.factorial(5)
m.pi
m.sqrt(5)
m.log(256, 2)

iii) from math import factorial

Here, we first call the from keyword, then math for the module. Next, we use the import keyword and call the specific function we would like to use.

print (factorial(5))

iv) from math import *

print(factorial(5))
print(pi)
print(sqrt(5)
print(log(256, 2))

5) User defined Modules in Python

i) Create a module

# A simple module, calc.py

price=1000

def add(x, y):
return (x+y)

def sub(x, y):
return (x-y)

def mul(x, y):
return (x*y)

ii) Use Module

# importing module calc.py

import calc

print calc.add(10, 2)

# from calc import mul

print(add(10, 2))

python tutorial

Python Tutorial for Beginners

G C Reddy

G C Reddy, Working as a Software Testing Trainer in Hyderabad, India.

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