Page 244 - Computer Science V2.0 Class 11

9 MODULES

Chapter Outline

9.1 Built-in Modules 9.2 User-defined Functions Revisited
9.3 User-defined Modules

Introduction

In the last chapter on Python Functions, we discussed several predefined built-in functions such as input(),
print(), int(), and abs(), dealing with input-output, data type conversion, and mathematical operations.
We also learnt to develop user-defined functions to perform some simple, useful tasks. However, Python also provides
specialised modules for specific tasks such as math and statistics, which provides several functions for
mathematical and statistical computations. Similarly, the random module provides several functions for random
number generation. We will also develop some user-defined functions. Sometimes, a user may like to specify values
of only the first few parameters because other parameters may take preassigned values. The preassigned values are
called default values, and the corresponding parameters are called default parameters. Also, there may be situations
where we need to specify only a few arguments, possibly in a sequence different from the list of formal parameters,
we will study the use of keyword arguments.

9.1 Built-in Modules

A Python module is just a Python script. Python provides several modules, each of which contains several useful
functions. Often, it is convenient to use predefined functions available in Python modules. However, to use these
functions, we need to import the relevant module using the following syntax:
import <modulename>
Once a module is imported, we can use all the functions defined in the module by preceding function name by the
name of the module and a dot(.) operator as shown below:

<modulename>.<functionname>()
For example, to use the sqrt() function defined in the math module, we first import the math module and then use
sqrt() function to find the square root of 25, as follows:

>>> import math
>>> math.sqrt(25)
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