Python programming Workshop SITTTR - Kalamassery

PYTHON PROGRAMMING
RIYAZ P A
Email : riyazaahil@gmail.com

TODAY’S CLASS
• Introduction
• What is Python ?
• Why Python ?
• Features
• Basics of Python
• Syntax
• Import
• Input Functions
• Output Functions
PYTHON PROGRAMMING 2

WHAT IS PYTHON ?
 Python is a widely used general-purpose, high-level programming
language.
 Python is simple and powerful language

WHY PYTHON ?

WHY PYTHON ?
Ease of Use and Powerful
Community Driven
Currently it’s in the top five programming languages in the
world according to TIOBE Index
Two times winner of Programming Language of the
Year(2007 and 2010) by TIOBE Index

FEATURES
 Simple
 Free and Open Source
 Powerful
 Object Oriented
 Dynamic, strongly typed scripting language
 Portable
 Interpreted

FEATURES
 Embeddable
 Extensive Libraries
 Scalable
Extensible

CAN DO
 Text Handling
 System Administration
 GUI programming
 Web Applications
 DatabaseApps
 Scientific Applications
 Games
 NLP
 ImageProcessing
 IoT and lot more …..

ZEN OF PYTHON

WHO USES PYTHON ?

RELEASES
 Createdin 1989 by Guido Van Rossum
 Python 1.0 releasedin 1994
 Python 2.7 is the recommendedversion
 3.0 adoption will take a fewyears

HELLO WORLD
hello_world.py
print('Hello, World!')

PYTHON 2 vs PYTHON 3
 print ('Python‘)
print 'Hello, World!'
 print('Hello, World!')
 In python 3 second statementwill show an error
File "", line 1
 print 'Hello, World!'
 ^
SyntaxError: invalid syntax

SAVING PYTHON PROGRAMS


COMMENTS
#Hello
‘’’ Hai
hello
‘’’

IMPORT
 When our program grows bigger, it is a good idea to break it into
different modules.
A module is a file containing Python definitions and statements.
 Python modules have a filename and end with the extension .py
 Definitions inside a module can be imported to another module
or the interactive interpreter in Python.
 . We use the import keyword to do this.

IMPORT
>>> import math
>>> math.pi
3.141592653589793
>>> from math import pi
>>> pi
3.141592653589793

IMPORT
 While importing a module, Python looks at several places defined in
sys.path.
 It is a list of directory locations.
 >>> import sys
>>> sys.path
['',
 'C:Python33Libidlelib',
 'C:Windowssystem32python33.zip',
 'C:Python33DLLs',
 'C:Python33lib',
 'C:Python33',
 'C:Python33libsite-packages']

SUM OF TWO NUMBERS
# Store input numbers
num1 = input('Enter first number: ') # input is built-in function
num2 = input('Enter second number: ') # input returns string
# Add two numbers
sum = float(num1) + float(num2)
# Display the sum
print('The sum of {0} and {1} is {2}'.format(num1, num2, sum))

FOR PYTHON 2
 from __future__ import print_function
 Type this in first line to avoid errors if you use python 2.

OUTPUT
>>> print('This sentence is output to the screen')
This sentence is output to the screen
>>> a = 5
>>> print('The value of a is',a)
The value of a is 5

OUTPUT…
For Python 3
print(1,2,3,4)
print(1,2,3,4,sep='*')
print(1,2,3,4,sep='#',end='&')
Output
1 2 3 4
1*2*3*4
1#2#3#4&

OUTPUT FORMATTING
 Sometimes we would like to format our output to make it look
attractive.
This can be done by using the str.format() method.
 This method is visible to any string object
>>> x = 5; y = 10
>>> print('The value of x is {} and y is {}'.format(x,y))
The value of x is 5 and y is 10

OUTPUT FORMATTING
>>> print('I love {0} and {1}'.format('bread','butter'))
I love bread and butter
>>> print('I love {1} and {0}'.format('bread','butter'))
I love butter and bread
>>> print('Hello {name},
{greeting}'.format(greeting='Goodmorning',name='John'))
Hello John, Goodmorning

OUTPUT FORMATTING
We can even format strings like the old printf() style used in C
programming language.
>>> x = 12.3456789
>>> print('The value of x is %3.2f' %x)
The value of x is 12.35
>>> print('The value of x is %3.4f' %x)
The value of x is 12.3457

AREA OF TRIANGLE
a = float(input('Enter first side: '))
b = float(input('Enter second side: '))
c = float(input('Enter third side: '))
# calculate the semi-perimeter
s = (a + b + c) / 2
# calculate the area
area = (s*(s-a)*(s-b)*(s-c)) ** 0.5
print('The area of the triangle is %0.2f' %area)

INPUT
Python 3
Syntax
input([prompt])
>>> num = input('Enter a number: ')
Enter a number: 10
>>> num
'10'

INPUT
Here, we can see that the entered value 10 is a string, not a number.
To convert this into a number we can use int() or float() functions.
>>> int('10')
10
>>> float('10')
10.0

INPUT EVAL
>>> int('2+3')
Traceback (most recent call last):
File "<string>", line 301, in runcode
File "<interactive input>", line 1, in <module>
ValueError: invalid literal for int() with base 10: '2+3'
>>> eval('2+3')
5

TEMPERATURE CONVERSION
# take input from the user
celsius = float(input('Enter degree Celsius: '))
# calculate fahrenheit
fahrenheit = (celsius * 1.8) + 32
print('%0.1f degree Celsius is equal to %0.1f degree Fahrenheit'
%(celsius,fahrenheit))

AVERAGE OF THREE NUMBERS
n1=float(input('1st num'))
n2=float(input('2nd num'))
n3=float(input('3rd num'))
avg=(n1+n2+n3)/3
print "Avarage os 3 numbers
{},{},{},={}n".format(n1,n2,n3,avg)
print ("Avarage os 3 numbers %0.2f %0.2f %0.2f%0.2f"
%(n1,n2,n3,avg))

KEYWORDS

DATA TYPES
 Strings
 Numbers
 Null
 Lists
 Dictionaries
 Booleans

Dictionaries

Dictionary Methods

Booleans

SQUARE ROOT
# Python Program to calculate the square root
num = float(input('Enter a number: '))
num_sqrt = num ** 0.5
print('The square root of %0.3f is %0.3f'%(num ,num_sqrt))

SQUARE ROOT - COMPLEX
# Find square root of real or complex numbers
# Import the complex math module
import cmath
num = eval(input('Enter a number: '))
num_sqrt = cmath.sqrt(num)
print('The square root of {0} is {1:0.3f}+{2:0.3f}j'.format(num
,num_sqrt.real,num_sqrt.imag))

OPERATORS
 Arithmetic
 String Manipulation
 Logical Comparison
 Identity Comparison
 Arithmetic Comparison

Arithmetic

String Manipulation

Logical Comparison

Identity Comparison

Arithmetic Comparison

VOLUME OF CYLINDER
from math import pi
r=input("Enter Radius")
h=input("Enter Height")
vol=pi*r**2*h
print (vol)

Avoid next line in print
Python 2.x
Print ”hai”,
Print ”hello”
Python 3.x
Print (‘hai’, end=‘’)
Print(‘hello’)

TODAY’S CLASS
• Intendation
• Decision Making
• Control Statements

INDENTATION
 Most languages don’t care about indentation
 Most humans do
 Python tend to group similar things together

INDENTATION
The else here actually belongs to the 2nd if statement

INDENTATION
I knew a coder like this

INDENTATION
You should always be explicit

INDENTATION
Python embraces indentation

DECISION MAKING
 Decision making is anticipation of conditions occurring while execution
of the program and specifying actions taken according to the conditions.
Decision structures evaluate multiple expressions which produce TRUE
or FALSE as outcome.
You need to determine which action to take and which statements to
execute if outcome is TRUE or FALSE otherwise.
assumes any non-zero and non-null values as TRUE, and if it is either
zero or null, then it is assumed as FALSE value.

DECISION MAKING

DECISION STATEMENTS
 If
 If Else
 If Elif
 Nested If

IF
var1=100
if True:
print ("1 - Got a true“)
print (var1)
var2=0
if var2:
print ("2- Got a true“)
print (var2)
print ("good bye“)

IF ELSE : ODD OR EVEN
num=input("number")
if num%2==0:
print (num,'is Even‘)
else:
print (num,'is Odd‘)

IF ELIF
num=input("Enter a number")
if num>0:
print (num,'is Positive‘)
elif num==0:
print (num,'is Zero‘)
else:
print (num,'is Negative‘)
print ('Have a nice day‘)

NESTED IF
num=input("Enter a number")
if num>0:
print (num,'is Positive')
else:
if num==0:
print (num,'is Zero')
else:
print (num,'is Negative')
print ('Have a nice day')

LARGEST OF THREE NUMBERS
a=input('1st number')
b=input('2nd number')
c=input('3rd number')
if (a>b) and (a>c):
large=a
elif (b>a) and (b>c):
large=b
else:
large=c
print ('The largest number is ',large)

QUADRATIC EQUATION
import cmath
print 'Enter the Coeifficents'
a=input("a")
b=input("b")
c=input("c")
delta=(b**2)-4*a*c
if delta>0:
sq=delta**0.5
x=(-b+sq)/(2.0*a)
y=(-b-sq)/(2.0*a)
print 'roots are n {} n {}'.format(x,y)
#Cont to next slide

QUADRATIC EQUATION …
elif delta==0:
x=-b/(2.0*a)
y=x
print 'roots are Equal'
print 'roots aren {} n {}'.format(x,y)
else:
print 'imaginary'
#delta=-delta
sqi=cmath.sqrt(delta)
x=-b/(2.0*a)
#print x
print 'roots are n {0} + {1} j n {0} - {1} j
'.format(x,sqi.imag)
#print sqi.imag

LOOPS
 For
 While
 While else
 While Infinite Loop
 While with condition at top, middle and bottom

FOR
sum=0
for i in range(11):
print i
sum+=i
print ('sum=',sum)

FOR
start=input('Enter start')
stop=input('stop')
stepindex=input('step')
for i in range(start,stop+1,stepindex):
print (i)

NUMBERS DIV BY 7 and 2
num=[]
for i in range(100,1000):
if i%7==0:
num.append(i)
print (num)
print ('nnn')
num2=[]
for i in num:
if i%2==0:
num2.append(i)
print (num2)

FACTORIAL
num=input('Enter number')
f=1
if num==0:
print (f)
else:
for i in range(1,num+1):
#f*=i
f=f*i
print (f)

PRIME NUMBER
num=input('Enter number')
f=0
for i in range(2,(num/2)+1):
if num%i==0:
#print i
f=1
break
if f:
print (num,'is Not a Prime number‘)
else:
print (num,'is Prime number‘)

CONTINUE
num=[]
if i%7==0:
continue
num.append(i)
print (num)

PASS
num=[]
pass
For empty for loop, function and class , you need to use pass

WHILE LOOP
n=input('Enter a Number n')
sum=0
i=1
while i<= n:
sum+=i
i+=1
print ('The Sum is ',sum)

WHILE ELSE
count=0
while count<3:
print 'inside loop'
count+=1
else:
print 'outside loop'

INFINITE LOOP
i=1 # Use Ctrl+C to exit the loop.
#Do it carefully
while True:
print i
i=i+1

VOWEL
vowels="aeiouAEIOU"
while True:
v=input("Enter a Char: ")
if v in vowels:
break
print ('not a vowel try again')
print ('thank you')

MULTIPLICATION TABLE
num=input('Enter Number: ')
i=1
while i<11:
print ('{} * {} = {}'.format(i,num,num*i))
i+=1

MULTIPLICATION TABLE
num=input('Enter Number: ')
print ('{} * {} = {}'.format(i,num,num*i))

LCM
n1=input('Enter 1st number ')
n2=input('Enter 2nd number ')
'''
if n1>n2:
lcm=n1
else:
lcm=n2
'''
lcm=max(n1,n2)
while True:
if (lcm%n1==0) and (lcm%n2==0):
break
lcm+=1
print ('LCM of {} and {} is {}'.format(n1,n2,lcm))

STUDENT GRADE
name=raw_input('Enter Student Name: ')
gpa=input('Enter GPA: ')
if gpa>=9:
print ('{} has got {} Grade'.format(name,'S'))
elif gpa>=8 and gpa<9 :
print ('{} has got {} Grade'.format(name,'A'))
elif gpa>=7 and gpa <8 :
print ('{} has got {} Grade'.format(name,'B'))
elif gpa>=6 and gpa<7:
print ('{} has got {} Grade'.format(name,'C'))
elif gpa>=5 and gpa<6:
print ('{} has got {} Grade'.format(name,'D'))
else:
print ('{} is Failed'.format(name))

DAYS WITH FUNCTION
days={
1:'Sun',
2:'Mon',
3:'Tue',
4:'Wed',
5:'Thu',
6:'Fri',
7:'Sat'
}
def day(d):
if days.get(d):
print ('Day is ',days.get(d))
else:
print ('Invalid Key ‘)
d=input('Enter the Day: ')
day(d)

SUM OF DIGITS
n=input('Enter the Number: ')
s=0
while n>0:
# a=n%10
# print a
s+=n%10
n/=10
print ('Sum of digit is ',s)

PALINDROME NUMBER
rev=0
n1=n
while n>0:
rev=rev*10+n%10
n/=10
print ('Reverse of Number is ',rev)
if rev==n1:
print ('Palindrome‘)
else:
print ('Not Palindrome‘)

ANTIGRAVITY
Import antigravity

TODAY’S CLASS
• Functions
• Namespace
• Name Binding
• Modules
• Packages

TARGET SCENARIO

BUILDING BLOCKS

DIVISION OF LABOUR

ASSEMBLY LINE

DIVIDE AND CONQUER

DIVIDE AND CONQUER
every problem can be broken down into smaller/more manageablesub-
problems
most computer programs that solve real-world problems are
complex/large
the best way to develop and maintain a large program is to construct it
from smaller pieces or components

PYTHON PROGRAM
COMPONENTS
 functions
classes
modules
 collectionof functions& classes
packages
 collectionof modules

PYTHON PROGRAM
COMPONENTS
Package
Module
Function
Class

FUNCTIONS
collection or block of statements that you can execute
whenever and wherever you want in the program

FUNCTIONS

WHY FUNCTIONS
 avoids duplicating code snippets
 saves typing
 easier to change the program later

FUNCTIONS
def function_name(parameters):
"""docstring"""
statement(s)

USER DEFINED FUNCTIONS

RETURN KEYWORD

VARIABLE SCOPE
x = “Rahul”
def kerala():
x =“Suresh”
print (x)
kerala()
print x

PYTHON FUNCTIONS (PARAMS vs
ARGS)

Function Parameters
Function Arguments

PYTHON FUNCTIONS
(ARGUMENTS)
 You can call a function by using the following types of formal
arguments:
 Required Arguments
 Default Arguments
 Keyword Arguments
 Variable-Length Arguments

REQUIRED ARGUMENTS

Required/MandatoryArguments passed to a function in correct positionalorder
def sum(x,y):
return x+y
print sum(2, 3)

DEFAULT ARGUMENTS

assumes a default value if a value is not provided in the function call for
that argument.
def sum(x=1,y=1):
return x+y
print sum()
print sum(2, 3)
print sum(x=2)
print sum(x=2, y=3)
print sum(y=3, x=2)

KEYWORD ARGUMENTS

the caller identifies the arguments by the parameter name as keywords,
with/without regard to positional order
def sum(x,y):
return x+y
print sum(y=3, x=2)

VARIABLE ARGUMENTS

can handleno-argument, 1-argument, or many-argumentsfunction calls
def sum(*addends):
total=0
for i in addends:
total+=i
return total
print sum()
print sum(2)
print sum(2,3)
print sum(2,3,4)

TRY IT OUT
 Program to find the sum of digits

FIBONACCI
# Fibonacci numbers module
def fib(n): # write Fibonacci series up to n
a, b = 0, 1
while b < n:
print b,
a, b = b, a+b
def fib2(n): # return Fibonacci series up to n
result = []
a, b = 0, 1
while b < n:
result.append(b)
a, b = b, a+b
return result

SUM_AB FUNCTION
def sumab(a,b):
sum=0
for i in range(a,b+1):
sum=sum+i
return sum

MATRIX
# Read the Matrix
def readmat(r,c):
mat=[]
for i in range(r):
temp=[]
for j in range(c):
temp.append(n)
mat.append(temp)
return mat
# Calculate the sum
def matsum(r,c,a,b):
res=[]
for i in range(r):
temp=[]
for j in range(c):
sum=a[i][j]+b[i][j]
# print sum
temp.append(sum)
res.append(temp)
# print res
return res

MATRIX…
# Print Matrix
def printmat(r,c,a):
print 'The Matrix is n '
for i in range(r):
for j in range(c):
print a[i][j],"t",
print 'n '
print "nn"
# Find Transponse
def transpose(r,c,a):
trans=[]
for i in range(c):
tmp=[]
for j in range(r):
tmp.append(0)
trans.append(tmp)
for i in range(c):
for j in range(r):
trans[i][j]=a[j][i]
return trans

MATRIX…
# Main pgm
r=input('Enter no. of rows: ')
c=input('Enter no. of cols: ')
#print 'Enter 1 st matrix n'
a=readmat(r,c)
print 'Enter 2nd matrix '
b=readmat(r,c)
res=matsum(r,c,a,b)
print 'The First Matrix'
printmat(r,c,a)
print 'The Second Matrix'
printmat(r,c,b)
print 'The Sum of Matrix'
printmat(r,c,res)
print 'The trnsponse Matrix'
t=transpose(r,c,res)
printmat(c,r,t)

NAMESPACES
refers to the current snapshot of loaded
names/variables/identifiers/folders
 functions must be loaded into the memory before you
could call them, especially when calling external
functions/libraries

NAMESPACES
import math
print dir()

NAMESPACES
import math, random
print dir()

FROM NAMESPACES
IMPORTING FUNCTIONS
from math import sin, cos, tan
print dir()

NAME BINDING
Import math as m
print m.sqrt()
from math import sqrt as s
print s(2)

Handling Modules
#Create demo.py
import my_module
#Create my_module.py
Print(“Entering My Module”)
Print(“Exiting My Module”)

* groups related modules
* code calling in several locations
* prevents name collision

HANDLING PACKAGES

HANDLING OF PACKAGES
The __init__.py files are required to make Python treat the directories
as containing packages

HANDLING OF PACKAGES:
WILL NOT WORK

WILL WORK

SUMMARY
IMPORTATION INVOCATION
importp1.p2.m p1.p2.m.f1()
from p1.p2 importm m.f1()
fromp1.p2.m import f1 f1()

Divide-and-Conquer is Powerful!

SYNTAX ERRORS
 Syntax errors, also known as parsing errors
perhaps the most common kind of complaint you get while you are still
learning Python:
>>> while True print 'Hello world'
File "<stdin>", line 1, in ?
while True print 'Hello world'
^
SyntaxError: invalid syntax

EXCEPTIONS
Even if a statementor expression is syntactically correct, it may cause
an error when an attemptis made to execute it.
Errors detected during execution are called exceptions and are not
unconditionally fatal: you will soon learn how to handle them in Python
programs.
>>> 10 * (1/0)
Traceback (most recent call last):
File "<stdin>", line 1, in ?
ZeroDivisionError: integer division or modulo by zero

EXCEPTIONS
try:
◦ (statements)
except(ValueError)

EXCEPTIONS
import sys
try:
f = open('myfile.txt')
s = f.readline()
i = int(s.strip())
except IOError as e:
print "I/O error({0}): {1}".format(e.errno,e.strerror)
except ValueError:
print "Could not convert data to an integer."
except:
print "Unexpected error:", sys.exc_info()[0]
raise

CLASSES
A class is just like a blueprint of a house.
An object is the actual house built from that blueprint.
You could then create numerous houses/objects from a single blueprint.

CLASS
class ClassName:
<statement-1>
.
.
.
<statement-N>

CLASS Example
class A:
def __init__(self):
pass
def somefunc(self, y):
x=4
c=x+y
print c
b= A()
A.somefunc(b,4) #Classname.method(object, variables)

riyazaahil@gmail.com

THANK YOU

Python programming Workshop SITTTR - Kalamassery

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