Chapter 03 python libraries

Unit I
Programming and Computational
Thinking (PCT-2)
(80 Theory + 70 Practical)
DCSc & Engg, PGDCA,ADCA,MCA.MSc(IT),Mtech(IT),MPhil (Comp. Sci)
Department of Computer Science, Sainik School Amaravathinagar
Cell No: 9431453730
Praveen M Jigajinni
Prepared by
Courtesy CBSE
Class XII

INTRODUCTION
A Module is a file containing python definitions,
functions, variables, classes and statements with .py
extension.
Python package is a directory of python module.
A Library is a collection of various packages.
There is no difference between library and python
package. Library is used to loosely describe a
collection of core or main modules.

COMPONENTS OF PYTHON PROGRAM
A Module is a file that contains python code.
The python program comprises of three main
components
i) Library or Package
ii) Module
iii) Functions/Sub-Modules

ADVANTAGES OF MODULES
1. Reusability
2. Clarity
3. Classification/ Grouping of code
4. Easy to understand

IMPORTING MODULES
t
Python module files have an extension .py
These modules can be imported in the following
ways:
1) import statement
2) from statement
3) from * statement

IMPORTING MODULES- import
t
import statement is used to include the modules
in other programs.
syntax : import <filename>
example: import math
more than one module can be
inserted in a python program
syntax : import <filename> ,<filename>,
<filename>……..
for example: import math,os

IMPORTING MODULES- import
t
using import statement one can view all the
functions and other attributes of a particular
module
for example: import math
dir(math)

IMPORTING MODULES- from
t
importing module can be done using from
statement specific attributes can be included in
other programs.
syntax :
from <filename> import function name
example:
from math import math.sqrt

IMPORTING MODULES- from*
t
from* statement can be used to import all
names from the module in to the current calling
name space.
syntax :
from <filename> import *
example:
from math import *
math.sqrt(4)
we can access any function by using dot
notation.

NAMESPACES
t
When we import modules in a particular
program these modules will become part of that
program and are called as namespace.
Python impliments namespaces in the form of
dictionaries. It maintains a name to object mapping.
There are three types of namespaces
1) Global
2) Local
3) Built in

NAMESPACES
Built in name space
Global name space
Local name
space

NAME RESOLUTION
t9lo
Already we know the scope rules of python
programming.
For every name reference within a
program when you access a variable python follows
name resolution rule i.e LEGB (Local, Enclosed,
Global, Built-in)
Contd.. Next slide

NAME RESOLUTION
Built in name space
Global name space
Local name space
Enclosed

MODULE ALIASING
t9lo
One can create an alias while importing module
in a program
syntax:
import <filename> as <alias name>
for example: import math as m
m.sqrt(4)

MEMBER ALIASING
t9lo
Like module aliasing members are also aliased
syntax:
import <filename> as <alias name>,
member as alias name
for example: import test as t, add as sum
test.py is module file and is
referred to as t and add is the function, it is referred
to as sum.

PACKAGE/LIBRARY
t9lo
Python packages are the collection of related
modules. You can import a package or create your
own.
The main difference between a module
and a package is that package is a
collection of modules and has an
__init__.py file

PACKAGE/LIBRARY
t9lo
Python package is a simply directory of python
modules
Steps to create and import a package
1. create a directory named ‘Gemetry’
2. add modules area.py and volume.py
3. create a file __init__.py in directory
‘Geometry’. The __init__.py files are
required to make python treat the
directory as containing package

PACKAGE/LIBRARY
GEOMETRY
Area.py Volume.py
FOLDER
FILES

PACKAGE/LIBRARY
FOLDER IS CREATED

PACKAGE/LIBRARY
AREA MODULE IS CREATED

PACKAGE/LIBRARY
VOLUME MODULE IS CREATED

PACKAGE/LIBRARY
CREATING __init__.py FILE

PACKAGE/LIBRARY
__init__.py FILE
What is __init__.py file?
__init__.py is simply a file used to
consider directories on the disk as
package of python.
It is basically used to initilize the
python package

PACKAGE/LIBRARY
Python searches module in the
following manner
1) Searches in current directory
2) If the module is not found then
searches each directory in the shell
variable PYTHONPATH
3) If all else fails, python checks the
default path which is the installation
location of the python

What is pip?
pip is a package-management
system used to install and manage
software packages written in Python.
To check pip version run,
pip --version at dos prompt

PYTHON STANDARD LIBRARY
DATE AND TIME MODULE.
import datetime
v_date=datetime.date.today()
vyear = v_date.year()
vmonth = v_date.month()
vday = v_date.day()

PYTHON STANDARD LIBRARY
DATE AND TIME MODULE.
import datetime
v_date=datetime.date.today()
vnow = v_date.now()
vhour = v_date.hour()
vmin = v_date.minute()
vsec = v_date.second()

CLASS TEST
1. What are the components of python program.
2.Explain the ways to import a module in
python program.
3.What is namespace? Explain in detail
4. What is python package? Write down the
steps to create a python package and also write
a programs and create a package.
Class : XII Time: 40 Min
Topic: Python Libraries Max Marks: 40
Each Question carries 5 Marks

Chapter 03 python libraries

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