Introducing Python Modules · •A book is generally divided into chapters. Why? •If it is not...
Transcript of Introducing Python Modules · •A book is generally divided into chapters. Why? •If it is not...
Introducing Python Modules Based on CBSE Curriculum
Class -11
By-Neha TyagiPGT CSKV 5 Jaipur II ShiftJaipur Region
Neha Tyagi, PGT CS II Shift Jaipur
Introduction
Neha Tyagi, PGT CS KV 5 Jaipur II Shift
• A book is generally divided into chapters. Why?
• If it is not divided into chapters, reading will be boring
and problematic.
• Similarly, a big program is generally divided into small
units, which are known as modules.
• The process of dividing a big program into small
modules is known as modularity.
• A module is itself an individual unit.
Introduction
Neha Tyagi, PGT CS KV 5 Jaipur II Shift
• Modularity decreases complexity of a program.
• Modularity also enhance the capability of Reusability .
• In this chapter we will discuss modularity in python and
about python modules.
Functions
Neha Tyagi, PGT CS KV 5 Jaipur II Shift
• Imagine a Math’s formula say 3x2
x = 1 will result into 3 X 12 = 3
x = 2 will result into 3 X 22 = 12
x = 3 will result into 3 X 32 = 27
means f(x) = 3x2
• We can say f(x) = 3x2 is a function where function is f, x is its
argument and 3x2 is its functionality. Function completes its
working and afterwards returns a result.
• Programming languages also supports functions.
A function-
• Can have arguments.
• Can perform Functionality.
• Can return result.
For ex-
def Calc(x):
r = 3*x**2
return r
Functions
Neha Tyagi, PGT CS KV 5 Jaipur II Shift
• def is the keyword to declare a function.
• calc is name of function.
• Varibale inside “ ( ) “ is argument or parameter.
• colon ‘:’ specifies end of line and starting of function block.
• The block contains whole functionality of the function. Here r = 3 * x ** 2
is the functionality of calc function. The part which is not inside
indentation is not the part of function.
• ‘return’ statement returns the computed result.
Carefully see the last example-
result
Functions Calling
Neha Tyagi, PGT CS KV 5 Jaipur II Shift
• Function calling statement or syntax
<FunctionName>(<ValueOfArgumentToBePassed>)
def Calc(x):
r = 3*x**2
return r
To call the function calc you need to write following statement-Calc(4) or A=5
Calc(A)
Python Function Type
Neha Tyagi, PGT CS KV 5 Jaipur II Shift
• In Python, functions are of 3 types-
• Built-in functions : These are ready to use pre defined functions.
For ex- len( ), type( ), int( ), input( ) etc.
1. Functions in Modules : These functions existes in
modules. To use such functions, you need to first
import the concerned module. like–sin( ) in math module .
2. User defined functions : These are developed by
programmer.
Structure of Python Module
Neha Tyagi, PGT CS KV 5 Jaipur II Shift
• A Python Module contains several things other than functions.
A Python file (.py file) can contain following objects-
Docstring : Triple Quoted comments which are important for
documentation.
Variables and constants : labels for data.
Classes : Blue print for objects.
Objects : Instances of classes.
Statements : Instructions
Functions :Group of instructions
Therefore we can say that if there is a module named ABC then
there should be a file named “ABC.py”.
• Module is an individual unit of data and code.
• It has the feature of reusability.
• It can depend on other modules also.
Python Module -Structure
Neha Tyagi, PGT CS KV 5 Jaipur II Shift
This module has 2 functions and 2 docstrings.|
Importing module.
Using object of module.
docString starts and ends with triple quotes “”””.
Python Module-Structure
Neha Tyagi, PGT CS KV 5 Jaipur II Shift
help(<ModuleName>) is used to see complete documentation of module.
dir (<ModuleName>) shows name of all objects of a module.
Facts of docString :• First letter of a line should be capital.• Second line empty.• Information in third line.
Importing module in a Python program
Neha Tyagi, PGT CS KV 5 Jaipur II Shift
• Import statement can be used in two forms-
1. Importng complete module-
import module1, module 2, . . . .
• For ex:
>>>import math
>>>import math,time etc
To use it’s object then-
<moduleName>.<functionName>
2. Importing selected objects from a module.-
from <module> import<objectname1>,<>. . .
Here, first pi value showed error. But when it is used after importing math module then all errors gets resolved.
Namespace
Neha Tyagi, PGT CS KV 5 Jaipur II Shift
• A namespace is a place to keep all names. It can understand with
following example-
• Suppose students from different KVs are participating in regional sports
meet.
If a name say Rahul is called-
There may be many students with the name Rahul which will create
confusion. Correct way of calling here should be Rahul from KV 5 Jaipur.
• Hence, KV 5 Jaipur is a namespace for Rahul here.
• This way of namespace resolves confusion.
• Similarly in python, namespace is an environment to keep logical group
of related objects.
• Python creates a namespace with the name of module itself.
• When two modules comes together then it gives a manner to write two
similar objects, which is as under-
• <ModuleName>.<ObjectName> Example : >>>math.sqrt(4)
Processing of import <module> command
Neha Tyagi, PGT CS KV 5 Jaipur II Shift
• When you run import <module> command, following tasks takes place-
• Code of imported module executed after interpretation.
• All programs and variables of the imported modules comes in the
present program.
• A namespace is set up with the name of imported module itself.
Processing of from <module> import <object>command
• When you run from<module> import <object> command, following
tasks takes place-
• Code of imported module executed after interpretation.
• Only selected (asked for) programs and variables of the imported modules
comes in the present program.
• No new namespace is created. Imported objects appends in the present
namespaceहैं |
Thank you
Please follow us on our blog
Neha Tyagi, KV 5 Jaipur II Shift
www.pythontrends.wordpress.com