Python_in_Detail

Python – An Introduction
Mahalakshmi Arulalan
Assistant Professor I
Galgotias University

Python is a Programming Language

so many
Programming Languages.
Why Python?

Python is simple and beautiful

Python is Free Open Source Software

What Can we Do?
● Text Handling
● System Administration
● GUI programming
● Web Applications
● Database Apps
● Scientific Applications
● Games
● NLP
● ...

Mayavi: 3D Visualization of
Scientific Data

Reference
➢https://www.itschool.gov.in/pdf/Std_X/ICT/xEnglish.pd
➢https://timesofindia.indiatimes.com/city/chennai/p
ython-replaces-c-java-in-new-cbse-
curriculum/articleshow/63421271.cms

Python – Hello World

Guido van Rossum
Father of Python
1991

Perl Java Python Ruby PHP
1987 1991 1993 1995

Python is...
A dynamic,open source
programming language with a focus on
simplicity and productivity. It has an
elegant syntax that is natural to
read and easy to write.

Quick and Easy
Intrepreted Scripting Language
Variable declarations are unnecessary
Syntax is simple
Memory management is automatic

print “Hello World”

Python – variable

Variables
colored_index_cards

No Need to Declare Variable Types !
Python Knows Everything !

value = 10
print value
value = 100.50
print value
value = “This is String”
print value * 3

name = raw_input(“What is Your name?”)
print "Hello" , name , "Welcome"

You have to follow
the Indentation
Correctly.
Otherwise,
Python will beat
you !

Discipline
Makes
Good

if score >= 5000 :
print “You win!”
elif score <= 0 :
print “Game over.”
else:
print “Current score:”,score
print “Donen”

Python – for loop

Python – Help usage
SEECE

Conversion
● Type int(x) to convert x to a plain integer.
● Type long(x) to convert x to a long integer.
● Type float(x) to convert x to a floating-point
number.
● Type complex(x) to convert x to a complex
number with real part x and imaginary part zero.
● Type complex(x, y) to convert x and y to a
complex number with real part x and imaginary
part y. x and y are numeric expressions

Python – Strings
SEECE

● + Concatenation - a + b will give HelloPython
● * Repetition -HelloHello
● [] Slice - a[1] will give e
● [ : ] Range Slice - Gives the characters from
the given range a[1:4] will give ell
Operators in stringsOperators in strings

List = Array
numbers = [ "zero", "one", "two", "three",
"FOUR" ]

List = Array
numbers = [ "zero", "one", "two", "three",
"FOUR" ]
numbers[0]
>>> zero
numbers[4]                                 numbers[1]
>>> FOUR                                  >>> FOUR
                         numbers[2]
          >>> three

Multi Dimension List
numbers = [ ["zero", "one"],["two", "three",
"FOUR" ]]
numbers[0]
>>> ["zero", "one"]
numbers[0][0]                       numbers[1][1]
>>> zero                                  >>> FOUR
                         len(numbers)
          >>> 2

Sort List
primes = [ 11, 5, 7, 2, 13, 3 ]

Sort List
primes = [ 11, 5, 7, 2, 13, 3 ]
primes.sort()

Sort List
primes = [ 11, 5, 7, 2, 13, 3 ]
primes.sort()
>>> [2, 3, 5, 7, 11, 13]

Sort List
names = [ "Shrini", "Bala", "Suresh",
"Arul"]
names.sort()
>>> ["Arul", "Bala","Shrini","Suresh"]
names.reverse()
>>> ["Suresh","Shrini","Bala","Arul"]

Mixed List
names = [ "Shrini", 10, "Arul", 75.54]
names[1]+10
>>> 20
names[2].upper()
>>> ARUL

Append on List
numbers = [ 1,3,5,7]
numbers.append(9)
>>> [1,3,5,7,9]

menu = {
“idly” : 2.50,
“dosai” : 10.00,
“coffee” : 5.00,
“ice_cream” : 5.00,
100 : “Hundred”
}
menu[“idly”]
2.50
menu[100]
Hundred

Example Programms
1.Square root program

names = ('Arul','Dhastha','Raj')
name.append('Selva')
Error : Can not modify the tuple
Tuple is immutable type

def sayHello():
print 'Hello World!' # block belonging of fn
# End of function
sayHello() # call the function

def printMax(a, b):
        if a > b:
                print a, 'is maximum'
        else:
                print b, 'is maximum'
printMax(3, 4)

#!/usr/bin/python
# Filename: using_sys.py
import time
print 'The sleep started'
time.sleep(3)
print 'The sleep finished'

#!/usr/bin/python
import os
os.listdir('/home/arulalan')
os.walk('/home/arulalan')

#!/usr/bin/python
# Filename: mymodule.py
def sayhi():
print “Hi, this is mymodule speaking.”
version = '0.1'
# End of mymodule.py

#!/usr/bin/python
# Filename: mymodule_demo.py
import mymodule
mymodule.sayhi()
print 'Version', mymodule.version

#!/usr/bin/python
# Filename: mymodule_demo2.py
from mymodule import sayhi, version
# Alternative:
# from mymodule import *
sayhi()
print 'Version', version

class Person:
pass # An empty block
p = Person()
print p
Classes

class Person:
def sayHi(self):
print 'Hello, how are you?'
p = Person()
p.sayHi()
Classes

class Person:
        def __init__(self, name):
#like contstructor
                self.name = name
        def sayHi(self):
                print 'Hello, my name is', self.name
p = Person('Arulalan.T')
p.sayHi()
Classes

class A:
        def hello(self):
print  ' I am super class '
class B(A):
def  bye(self):
print  ' I am sub class '
p = B()
p.hello()
p.bye()
Classes

class A:
Var = 10
def __init__(self):
self.public = 100
self._protected_ = 'protected'
self.__private__ = 'private'
Class B(A):
pass
p = B()
p.__protected__
Classes

poem = ''' Programming is fun
When the work is done
if you wanna make your work also fun:
use Python!
'''
f = file('poem.txt', 'w') # open for 'w'riting
f.write(poem) # write text to file
f.close()

f= file('poem.txt','r')
for line in f.readlines():
print line
f.close()

import psycopg2

conn = psycopg2.connect(" dbname='pg_database'
user='dbuser' host='localhost' password='dbpass' ")
cur = conn.cursor()
cur.execute("""SELECT * from pg_table""")
rows = cur.fetchall()
print rows
cur.close()
conn.close()

import psycopg2

conn = psycopg2.connect(" dbname='pg_database'
user='dbuser' host='localhost' password='dbpass' ")
cur = conn.cursor()
cur.execute("'insert into pg_table values(1,'python')"')
conn.commit()
cur.close()
conn.close()

Python – Shell

● Interactive Python
● Instance Responce
● Learn as you type

bpython
ipython

}
teach you very easily

Python can communicate
                 With
                Other
            Languages

Python_in_Detail

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