Python for High School Programmers

Sivasubramaniam Arunachalam

April 06, 2013

@sivaa_in

It’s me!

• Application Developer

• Web/Enterprise/Middleware/B2B

• Java/Java EE, Python/Django

• 2002

• Technical Consultant

• Process Mentor • Speaker

It’s about you!

Have you written a code recently?

Yes / No / Never

It doesn’t matter!

Agenda

• Background

• Concepts

• Basics

• Demo

for / else

for ( int i = 0; i < 10; i++ ) {

……

} else {

……

}

Back in 1989

http://www.python.org/~guido/images/guido91.gif

Guido van Rossum

https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcRsHF89zT2tSdsm45hFYDaJPocfpwIM_Eh76pjKbTzZI2dxArWa

http://upload.wikimedia.org/wikipedia/en/9/9a/CompleteFlyingCircusDVD.jpg

High Level Language

Dynamic / Scripting Language

• Beautiful is better than ugly.

• Explicit is better than implicit.

• Simple is better than complex.

• Complex is better than complicated.

• Flat is better than nested.

• Sparse is better than dense.

• Readability counts.

• Special cases aren't special enough to break the rules.

• Although practicality beats purity.

• Errors should never pass silently.

• Unless explicitly silenced.

• In the face of ambiguity, refuse the temptation to guess.

• There should be one-- and preferably only one --obvious way to do it.

• Although that way may not be obvious at first unless you're Dutch.

• Now is better than never.

• Although never is often better than *right* now.

• If the implementation is hard to explain, it's a bad idea.

• If the implementation is easy to explain, it may be a good idea.

• Namespaces are one honking great idea -- let's do more of those!

Zen of Python

Why?

Clean / Clear Syntax

Less Key Words

31

Portable

• Servers / Desktops / Mobile Devices / Raspberry Pi • Windows/Unix/Linux/Mac • Pre-installed in Mac and Linux

Multi-Language Support

• CPython • Jython • IronPython

Multi-Paradigm

• Functional / Procedural / Object Oriented

Easy to Learn

Highly Readable

No Variable Declaration

More Productivity

...the lines of Python code were 10% of the equivalent C++ code. - Greg Stein

Batteries Included

Open Source

Where I can use? • Stand-Alone Application

• Desktop/GUI Application

• Web Application

• XML Processing

• Database Application

• Network Application

• Scientific Application

• Gaming

• Robotics

Some One using it?

Hello World!

Installation / Tools

• Interpreter • Script Editor

.py .pyc .pyo .pyd

Optimized Code

• Faster Execution • Less CPU Cycles

Increment ‘i’ by 1

i++

i = i + 1

ADD #1,A1 [A1] ← [A1] + 1

Machine Instructions

/

Line of Code (LoC)

Assembly Language

System Languages

Scripting Languages

1 - 2

3 - 7

100 - 1K

Current Versions

2.7.3 & 3.3.0

The Prompt

>>>

How to run?

C:\> python my_program.py

• Start / Exit

• Simple print

• Zen of Python

• Keywords

• Help

Let’s Start

Variables

int int_ex = 10;

<type> var_name = val;

int_ex = 10

int_ex = 10

long_ex = 1000000000000L

float_ex = 1.1

string_ex = “Welcome”

boolean_ex = True

type()

print type(int_ex)

print type(long_ex)

print type(float_ex)

print type(string_ex)

print type(boolean_ex)

boolean_one = True

boolean_two = False

print boolean_one and boolean_two

print boolean_one or boolean_two

print not boolean_two

int_one = 11

int_two = 5

print int_one / int_two

print float(int_one) / float(int_two)

print float(int_one) / int_two

print int_one / float(int_two)

type casting

int_ex = 11

float_ex = 8.8

boolean_ex = True

print float (int_ex)

print int (float_ex)

print int (boolean_ex)

int_one = 11

int_two = 5

print int_one + int_two

print int_one - int_two

print int_one * int_two

print int_one / int_two

print int_one % int_two

print int_one ** int_two

int_one = 11

int_two = 5

print int_one > int_two

print int_one >= int_two

print int_one < int_two

print int_one <= int_two

print int_one == int_two

print int_one != int_two

Lets do some Maths

import math

(or)

from math import sqrt

dir (math)

int_one = 11

int_two = 5

import math

print math.sqrt (int_one)

from math import factorial

print factorial (int_two)

import math

print math.pi

Lets Talk to the User

raw_input()

(or)

raw_input([prompt_string])

user_input = raw_input()

print “You have Entered “ , user_input

user_input = raw_input(“Input Please : “)

print type(user_input)

int_one = raw_input (“Number 1 : “)

int_two = raw_input (“Number 2 : “)

print int_one + int_two

print int(int_one) + int(int_two)

The Nightmare Strings

“Hey, What’s up?”

‘ ’

“ ”

“““ ”””

‘‘‘ ’’’

print ‘ example text ’

print “ example text ”

print “““ example of long …..

…. text ”””

print ‘‘‘ example of long …..

…. text ’’’

print ‘ String with “double” quotes ’

print “String with ‘single’ quote ”

print “\“ Hey what‘s up\””

print ‘“ Hey what\‘s up\”’

print “““ “ Hey what‘s up ” ”””

print ‘‘‘ “ Hey what‘s up ” ’’’

Don’t Mess with Quotes

Collections

0 1 2 3 4 5

-6 -1 -2 -3 -4 -5

10.1 10 ‘A’ ‘ABC’ 2 True

0 1 2 3 4 5

-6 -1 -2 -3 -4 -5

10.1 10 ‘A’ ‘ABC’ 2 True

list_ex = [ 10, 10.1, ‘A’, ‘ABC’, 2, True ]

tuple_ex = ( 10, 10.1, ‘A’, ‘ABC’, 2, True )

List [] vs Tuple ()

0 1 2 3 4 5

-6 -1 -2 -3 -4 -5

10.1 10 ‘A’ ‘ABC’ 2 True

tuple_ex = ( 10, 10.1, ‘A’, ‘ABC’, 2, True )

• tuple_ex[0]

• tuple_ex[1]

• tuple_ex[2]

• tuple_ex[3]

• tuple_ex[4]

• tuple_ex[5]

• tuple_ex[-6]

• tuple_ex[-5]

• tuple_ex[-4]

• tuple_ex[-3]

• tuple_ex[-2]

• tuple_ex[-1]

Tuple / List Tricks

tuple_ex = (100, )

list_ex = [100, ]

tuple_ex = tuple(‘gobi’)

list_ex = list(‘gobi’)

Lets Slice!

0 1 2 3 4 5

-6 -1 -2 -3 -4 -5

9

list_ex = [1, 2, 3, 4, 5, 6, 7, 8, 9 , 10, ]

print list_ex[:3]

print list_ex[3:]

print list_ex[:-3]

print list_ex[-3:]

6 7 8 9

1 2 3 4 5 6 7 8 10

-7 -8 -9 -10

0 1 2 3 4 5

-6 -1 -2 -3 -4 -5

9

list_ex = [1, 2, 3, 4, 5, 6, 7, 8, 9 , 10, ]

print list_ex[0:1]

print list_ex[0:2]

print list_ex[-2:-1]

print list_ex[-3:-1]

6 7 8 9

1 2 3 4 5 6 7 8 10

-7 -8 -9 -10

0 1 2 3 4 5

-6 -1 -2 -3 -4 -5

9

list_ex = [1, 2, 3, 4, 5, 6, 7, 8, 9 , 10, ]

print list_ex[0:10:2]

print list_ex[1:10:2]

6 7 8 9

1 2 3 4 5 6 7 8 10

-7 -8 -9 -10

0 1 2 3 4 5

-6 -1 -2 -3 -4 -5

9

list_ex = [1, 2, 3, 4, 5, 6, 7, 8, 9 , 10, ]

print len(list_ex)

print max(list_ex)

print min(list_ex)

6 7 8 9

1 2 3 4 5 6 7 8 10

-7 -8 -9 -10

Lets Join!

city = list(‘gobi’)

city[len(city):] = “chettipalayam”

“”.join(city)

ipl_teams = [‘CSK’, ‘DD’, ‘KXIP’, ‘KKR’, ‘MI’, ‘PWI’, ‘RR’, ‘RCB’, ‘SRH’,]

“, ”.join(ipl_teams)

str_ipl_teams = “, ”.join(ipl_teams)

list_ipl_teams = list(str_ipl_teams )

list_ipl_teams[str_ipl_teams.rfind(", ")] = " and“

print "".join(list_ipl_teams)

ipl_teams = [‘CSK’, ‘DD’, ‘KXIP’, ‘KKR’, ‘MI’, ‘PWI’, ‘RR’, ‘RCB’,]

ipl_teams.append(‘SRH’)

ipl_teams = [‘CSK’, ‘DD’, ‘KXIP’, ‘KKR’, ‘MI’, ‘PWI’, ‘RR’, ‘RCB’,]

ipl_teams.remove(‘SRH’)

del ipl_teams[-1]

ipl_teams = [‘CSK’, ‘DD’, ‘KXIP’, ‘KKR’, ‘MI’, ‘PWI’, ‘RR’, ‘RCB’,]

ipl_teams.insert (1, ‘SRH’)

ipl_teams = [‘CSK’, ‘SRH’, ‘DD’, ‘KXIP’, ‘KKR’, ‘MI’, ‘PWI’, ‘RR’, ‘RCB’,]

ipl_teams.sort()

The Control Flow

Lets begin with a

Search

list_ex = [1, 2, 3, 4, 5]

print 3 in list_ex1

title_winners = [‘CSK’, ‘RR’, ‘DC’, ‘KKR’]

print ‘CSK’ in title_winners

my_city = “Gobichettipalayam”

print ‘chetti’ in my_city

while

i = 1

while i <= 10:

print i,

i = i + 1

for

for i in range(1, 11):

print i,

for i in range(11):

if i % 2 == 0: print i

for i in range(11):

if i % 2 == 0: print “Even : ”, i

else : print “Odd: ”, i

for i in range(11):

if i == 0: pass

elif i % 2 == 0: print “Even : ”, i

else : print “Odd: ”, i

for i in range(11):

if i == 0: continue

elif i % 2 == 0: print “Even : ”, i

else : print “Odd: ”, i

for i in range(11):

if i == 0: break

elif i % 2 == 0: print “Even : ”, i

else : print “Odd: ”, i

title_winners = ['CSK', 'RR', 'DC', 'KKR']

for team in title_winners:

print team,

for i in range(11):

print i,

else:

print “No Break executed in for”

Null Factor None

list_ex = []

if list_ex:

print “List is not Empty”

else:

print “List is Empty”

list_ex = None

if list_ex:

print “List is not None”

else:

print “List is None”

Error Handling

The OO Python

Thank You! siva@sivaa.in

bit.ly/sivasubramaniam bit.ly/sivaa_in

References

http://www.slideshare.net/narendra.sisodiya/python-presentation-presentation http://www.f-106deltadart.com/photo_gallery/var/albums/NASA-Research/nasa_logo.png?m=1342921398 http://www.seomofo.com/downloads/new-google-logo-knockoff.png http://www.huntlogo.com/wp-content/uploads/2011/11/US-Navy-Logo.png http://3.bp.blogspot.com/_7yB-eeGviiI/TUR471pyRpI/AAAAAAAAIBI/X705lo5Gjqc/s1600/Yahoo_Logo24.JPG http://www.thetwowayweb.com/wp-content/uploads/2012/09/youtube_logo.png