Python programming Workshop SITTTR - Kalamassery

PYTHON PROGRAMMING

RIYAZ P AEmail : [email protected]

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

Database Apps

Scientific Applications

Games

NLP

Image Processing

IoT and lot more …..


ZEN OF PYTHON



WHO USES PYTHON ?


RELEASES


Created in 1989 by Guido Van Rossum

Python 1.0 released in 1994



Python 2.7 is the recommended version

3.0 adoption will take a few years

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 statement will 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:\\Python33\\Lib\\idlelib',

'C:\\Windows\\system32\\python33.zip',

'C:\\Python33\\DLLs',

'C:\\Python33\\lib',

'C:\\Python33',

'C:\\Python33\\lib\\site-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 FORMATTINGWe 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)


INPUTPython 3

Syntax

input([prompt])

>>> num = input('Enter a number: ')

Enter a number: 10

>>> num

'10'


INPUTHere, 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


Strings


Numbers


Null


Lists


Lists


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 printPython 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

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=xprint 'roots are Equal'print 'roots are\n {} \n {}'.format(x,y)

else:print 'imaginary'#delta=-deltasqi=cmath.sqrt(delta)x=-b/(2.0*a)#print xprint '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 ('\n\n\n')

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‘)

ANTIGRAVITYImport antigravity


TODAY’S CLASS• Functions

• Namespace

• Name Binding

• Modules

• Packages


TARGET SCENARIO


BUILDING BLOCKS


DIVISION OF LABOUR


DIVISION OF LABOUR


ASSEMBLY LINE


DIVIDE AND CONQUER


DIVIDE AND CONQUERevery problem can be broken down into smaller/more manageable sub-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 collection of functions & classes

packages collection of modules


PYTHON PROGRAM COMPONENTS


Package

Module

Function

Class

FUNCTIONScollection or block of statements that you can execute

whenever and wherever you want in the program


FUNCTIONS


FUNCTIONS


WHY FUNCTIONS avoids duplicating code snippets

saves typing

easier to change the program later


FUNCTIONSdef function_name(parameters):

"""docstring"""

statement(s)


USER DEFINED FUNCTIONS


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/Mandatory Arguments passed to a function in correct positional order

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 handle no-argument, 1-argument, or many-arguments function calls

def sum(*addends):total=0for i in addends:

total+=ireturn 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 moduledef fib(n): # write Fibonacci series up to n

a, b = 0, 1while b < n:

print b,a, b = b, a+b

def fib2(n): # return Fibonacci series up to nresult = []a, b = 0, 1while 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 "\n\n"

# 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 pgmr=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)


NAMESPACESrefers 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


NAMESPACESimport math

print dir()


NAMESPACESimport math, random

print dir()


FROM NAMESPACES IMPORTING FUNCTIONSfrom math import sin, cos, tan

print dir()


NAME BINDINGImport 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 PACKAGESThe __init__.py files are required to make Python treat the directories as containing packages


HANDLING OF PACKAGES: WILL NOT WORK


HANDLING OF PACKAGES: WILL WORK






SUMMARY

IMPORTATION INVOCATION

import p1.p2.m p1.p2.m.f1()

from p1.p2 import m m.f1()

from p1.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


EXCEPTIONSEven if a statement or expression is syntactically correct, it may cause an error when an attempt is 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


EXCEPTIONStry:

◦ (statements)

except(ValueError)


EXCEPTIONSimport 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


OOP


OOP


CLASSESA 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.


CLASSclass 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)

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THANK YOU


Education

Python programming Workshop SITTTR - Kalamassery