Packages and Datastructures - Python

PACKAGES &
DATASTRUCTURES in
PYTHON
1
By
B.Hemalatha
Assistant Professor
VEC

PACKAGES / LIBRARY
 In Computer we store files in organized hierarchies
 Subdirectories
 Files
 Large projects in Python are organized as Packages
which consists of many
 Sub-Packages
 Similar Modules
 Packages makes projects easy to manage and conceptually clear
2

PACKAGES / LIBRARY
 Python package is a directory containing
 Sub-packages
 Modules
 Along with an __init__.py file
Python module
 Is a . py file
 Contains functions, variables
3
double underscore

Mensuration
Square.py
Rectangle.py
Circle.py
Eg 1. PACKAGE
4
M
O
D
U
L
E
S
Directory
Package

• Game Development Package Organization
Eg 2.PACKAGES / LIBRARY
5
PACKAGE
list
SUBPACKAGES
M
O
D
U
L
E
S

• Steps to create a package
– Create a directory with the package name
– Create modules under it
– Create a file __init__.py in the directory
Note : File __init__.py is a simple file required to make python treat the
directory on the disk as packages of python
• Access packages and its modules
– from PACKAGE_NAME import MODULE_NAME
• Access functions in modules
– Use dot operator “ . ”
– MODULE_NAME . FUNCTION_NAME
PACKAGES / LIBRARY
6

PACKAGES / LIBRARY
mensuration
square.py rectangle.py
Modules/
Python Files
Directory /
Package
Example:
7

Step1 : Folder/Directory Creation:
Folder/directory named “mensuration”
creation
Step 2: Module Creation - I: “square.py”
# Square Module
def area(side):
return side * side
def peri(side):
return 4 * side
PACKAGES / LIBRARY
8

Step 2 : Module Creation - II: “ rectangle.py”
# Rectangle Module
def area(length,breadth):
return length*breadth
def peri(length,breadth):
return 2*(length+breadth)
Step 3 : file __init__.py Creation
PACKAGES / LIBRARY
9

To Access Packages and its Modules
from mensuration import square,rectangle
To Access functions inside the Modules
square . area (side)
rectangle . area (length,breadth)
PACKAGES / LIBRARY
10
#Rectangle Module
def area(length,breadth):
def peri(length,breadth):
# Square Module
def area(side):
def peri(side):

1. Package in Python is a
– (a) File
– (b) Database
– (c) hierarchical file directory
– (d) hierarchical database directory
»(Ans: c)
11

2. To include a package in python we use
– (a) include statement
– (b) import statement
– (c) package include statement
– (d) package import statement
»(Ans: b)
12

3. A Package contains
– (a) sub-packages
– (b) modules
– (c)__init__.py
– (d) All the above
»(Ans: d)
4. Python supports built in packages
– (a) Yes
– (b) No
»(Ans: a)
13

5. The package folder contains a special file
called__________
– (a) __init__.py,
– (b) Pack_.py
– (c)_pack_,py
– (d)_init_pack_.py
»(Ans: a)
14

INTRODUCTION TO
DATA STRUCTURES
15

Data structure
 way to store and organize data
 helps in writing efficient programs in any
language
Python is a high-level, interpreted, interactive
and object-oriented scripting language using
which we can study the fundamentals of data
structure in a simpler way as compared to
other programming languages.
Data structure in Python
16

17
Data Structures in Python
Built-in Data Structures User-Defined Data Structures
List
Tuple
Dictionary
Set
Stack
Queue
Tree
Graph
Linked
list

Today we will focus on few Data Structures
1.Stacks
2.Queues
3.Graph
18

Stack
Data structure - Stack
19

Stack
 is an ordered collection of items
 addition of new items
 removal of existing items
 this ordering principle is called Last-In First-Out(LIFO)
A Stack of Books A Stack of Primitive Python Objects
20
always takes place at the same end
usually top

21
Stack
Insertion
“PUSH”
Deletion
“POP”
Top
LIFO PRINCIPLE

Stack using LIST in Python
22
Stack LIFO PRINCIPLE

Stack using LIST in Python
Example:
# empty stack
stack = [ ]
# push operation # pop operation
23
OUTPUT
stack.append(10) stack =[10]
stack.append(20) stack =[10,20]
stack.append(30) stack =[10,20,30]
OUTPUT
stack.pop() stack =[10,20,30]
stack.pop() stack =[10,20]
top
top
top
top
top

Data structure - Queue
24
QUEUE

Queue
 is an ordered collection of items
 Addition of new items happens at one end, called the “rear,”
 Removal of existing items occurs at the other end, called the “front.”
 This ordering principle is sometimes called First-In First-Out (FIFO)
A Queue of Python Data Objects
25

Insertion – Enqueue
Deletion - Dequeue
26
QUEUE
Rear Front
FIFO PRINCIPLE

Queue using LIST in Python
Example:
# empty queue
queue = [ ]
# enqueue operation # dequeue operation
27
OUTPUT
queue.append(10) queue =[10]
queue.append(20) queue =[10,20]
queue.append(30) queue =[10,20,30]
OUTPUT
queue.pop(0) queue =[10,20,30]
queue.pop(0) queue =[20,30]
rear
rear
front
front
rear

QUEUE APPLICATIONS – SHARING PRINTER RESOURCE
28
A
B
C
D
Job 1 Job 2
Job 3
Job 3 Job 2 Job 1
Printer queue
front

Data structure - Graph
Graph
Data is stored in a collection of vertices(nodes)
interconnected by edges (path)
29

Graph using DICTIONARY
Example:
# GRAPH structure
graph = { “a”:[“d”], “b”:[“c”],“c”:[“d”,”e”],
“d”: [“a”,”c”] ,”e”:[“c”]}
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Application –
Undirected Graph
31
• Social Network – FACEBOOK
Suggest Friends

Application – Directed Graph
32
• World Wide Web

1. Consider the following operation performed on a stack
Push(1);
Pop();
Push(2);
Push(3);
Pop();
Push(4);
Pop();
After the completion of all operation, the number of elements
present in stack are
- (a) 1
- (b) 2
- (c) 3
- (d) 4
»(Ans: a)
33

2. A list of elements in which deletion can be
done from one end (front) and insertion can
take place only at the other end (rear) is known
as
- (a) Queue
- (b) Stack
- (c) Tree
- (d) Linked list
»(Ans: a)
34

3. Google Map is an application of
- (a) Tree
- (b) Stack
- (c) Graph
- (d) Queue
»(Ans: c)
35

Packages and Datastructures - Python

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