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Keep Calm and Code Python

Let’s Python Department of Computing!Faculty of Science!Silpakorn University


Who am I ?

Kiattisak Anoochitarom!Graduated from Computer Science at SU, 2013!Software Developer at Charged Concept Co, LTD.!!Skill Sets: iOS, Rails, Node.js, Ruby, Python, Javascript, !C++, C, Java, Badminton!!Contacts:! [email protected]! Twitter: @iMacbaszii! http://www.facebook.com/baszii! http://www.macbaszii.com!

http://www.facebook.com/baszii

http://www.macbaszii.com

Who Invented ?

❖ Guido van Rossum!❖ Dutch!❖ 2005 - 2012 at Google inc.!❖ 2013 at Dropbox inc.

Langauge Characteristic


❖ Open Source (Python Software Foundation)



❖ Rapid Development




❖ Short and Readable Code





❖ Indentation!





❖ Indentation!

❖ Strong and Dynamic Typing





❖ Indentation!

❖ Strong and Dynamic Typing

❖ Interpreter Style

PEP - 8 Python Coding Style Guide

http://www.python.org/dev/peps/pep-0008/

Input & Output

Input & Output

name = raw_input()

print "Hello, %s" % (name)print "Hello, " + name

x = input()y = input()

print x * y

Input & Output

name = raw_input()

print "Hello, %s" % (name)print "Hello, " + name

x = input()y = input()

print x * yHands - on!!

Data Type

DictionaryString

Integer

Floating Point

None

List

Boolean

Class Instance

Set

Data Type

Dictionary

Integer

Floating Point

None

List

Boolean

Class Instance

Set

sentence = 'this is a cat'

Data Type

Dictionary

Floating Point

None

List

Boolean

Class Instance

Set


x = 20

Data Type

Dictionary

Floating Point

None

List

Class Instance

Set


x = 20

you_love_me = True

Data Type

Dictionary

None

List

Class Instance

Set


x = 20

pi = 3.1415927

you_love_me = True

Data Type

Dictionary

List

Class Instance

Set


x = 20

pi = 3.1415927

you_love_me = True

nothing = None

Data Type

Dictionary

Class Instance

Set


x = 20

pi = 3.1415927

you_love_me = True

nothing = None

even_numbers = [2, 4, 6, 8, 10]

Data Type

Dictionary

Class Instance


x = 20

pi = 3.1415927

you_love_me = True

nothing = None

even_numbers = [2, 4, 6, 8, 10]

odd_numbers = {1, 3, 5, 7, 9}

Data Type

Class Instance


x = 20

pi = 3.1415927

you_love_me = True

nothing = None

even_numbers = [2, 4, 6, 8, 10]

odd_numbers = {1, 3, 5, 7, 9}

profile = { 'name': 'Bas',\ 'email': '[email protected]'}

mailto:[email protected]

Data Type


x = 20

pi = 3.1415927

you_love_me = True

nothing = None

even_numbers = [2, 4, 6, 8, 10]

odd_numbers = {1, 3, 5, 7, 9}

profile = { 'name': 'Bas',\ 'email': '[email protected]'}

my_car = Car('Lamborghini',\ 'Aventador LP 700-4', 'White')

mailto:[email protected]

Operator

Math Operator

Math Operator

x = 10y = 20

x + yx - yx * yx / yx % yx**yx += yy *= x

Math Operator

x = 10y = 20

x + yx - yx * yx / yx % yx**yx += yy *= x

## Tips ##

int + int = intint**(-int) = floatint / float = floatstring + string = concat_stringstring * int = multiply_stringlist + list = list

Comparison Operator

Comparison Operator

x = 10y = 20

x > yx >= yx < yx <= yx == yx != yx is y

Comparison Operator

x = 10y = 20

x > yx >= yx < yx <= yx == yx != yx is y

# Chain Comparison5 < x < y1 < y < 100

# Contains Operatorprime = [2, 3, 5, 7, 11]9 in prime # False

sentence = 'this is a cat''cat' in sentence # True

Logical Operator

Logical Operator Although Python have & and | (pipe) to do logical operation !but it isn’t readable and it will confuse with other symbol. !But Python have special symbols to do logical operation that is …

Logical Operator Although Python have & and | (pipe) to do logical operation !but it isn’t readable and it will confuse with other symbol. !But Python have special symbols to do logical operation that is …

and, or

Range and Lazy Generator

Range and Lazy Generator

range(10)# [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]range(3, 10)# [3, 4, 5, 6, 7, 8, 9]range(1, 20, 3)# [1, 4, 7, 10, 13, 16, 19]

xrange(10)xrange(3, 10)xrange(1, 20, 3)

Control Statement

Conditional Statementif

Conditional Statement

number = input("Enter Number: ")

if number > 0:print "Number is Positive"

elif number < 0:print "Number is Negative"

else:print "Number is Zero"

if






if

result = (number % 2 == 0) ? 'Even' : 'Odd'






if

result = 'Even' if number % 2 is 0 else 'Odd'

Iteration Statementfor


for i in xrange(1, 11):print i**2



socials = ['Facebook', 'Twitter']for social in socials:

print 'I played %s' % social





message = 'Hello, CPSU'for letter in message:

print letter





# Endless Loop #while True:

# Do something

message = 'Hello, CPSU'for letter in message:

print letter

Problem#1: Most Letter CountHint: You can get list of alphabets with this code

import string !alphabets = list(string.lowercase)

Function

Functiondef function_name(params):

# Do something# Do anything



def fibonacci(n):fibo = 0for k in xrange(0, int(math.floor((n - 1) / 2)) + 1):

fibo += math.factorial(n - k - 1) /\(math.factorial(k) * math.factorial(n - k - 1 - k))

return fibo



def fibonacci(n):fibo = 0for k in xrange(0, int(math.floor((n - 1) / 2)) + 1):

fibo += math.factorial(n - k - 1) /\(math.factorial(k) * math.factorial(n - k - 1 - k))

return fibo

def colorMultiply(r, g=0, b=0):return [ r * 3.14159,\

g * 1.414,\b * 3.27 ]

Built-in Functionshttp://docs.python.org/2/library/functions.html

http://docs.python.org/2/library/functions.html

Problem#2: Make a Palindrome StringgnirtS emordnilaP

Sometimes some words like "localization" or "internationalization" are so long that writing them many times in one text is quite tiresome.!

Let's consider a word too long, if its length is strictly more than 10 characters. All too long words should be replaced with a special abbreviation.!

This abbreviation is made like this: we write down the first and the last letter of a word and between them we write the number of letters between the first and the last letters. That number is in decimal system and doesn't contain any leading zeroes.!

Thus, "localization" will be spelt as "l10n", and "internationalization will be spelt as “i18n".!

and make Palindrome from that word after that :)

http://codeforces.com/problemset/problem/71/A

Way Too Long Words

Indexing and Slice

Indexing and Slicemessage = 'Hello, world'message[0] # Hmessage[len(message) - 1] # dmessage[-1] # d


fibo = [1, 1, 2, 3, 5, 8, 13, 21, 34]fibo[:5] # [1, 1, 2, 3, 5]fibo[2:] # [2, 3, 5, 8, 13, 21, 34]fibo[3:6] # [3, 5, 8, 13]fibo[::2] # [1, 2, 5, 13, 34]


fibo[::-1] # ???message[::-1] # ???

fibo = [1, 1, 2, 3, 5, 8, 13, 21, 34]fibo[:5] # [1, 1, 2, 3, 5]fibo[2:] # [2, 3, 5, 8, 13, 21, 34]fibo[3:6] # [3, 5, 8, 13]fibo[::2] # [1, 2, 5, 13, 34]

String and Collections methods

Demo!

List ComprehensiveThe Other way to create and manipulation Python’s List

List Comprehensive

[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]

The Other way to create and manipulation Python’s List

List Comprehensive

squares = [] for x in range(10): squares.append(x**2)

[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]


List Comprehensive

squares = [x**2 for x in range(10)][0, 1, 4, 9, 16, 25, 36, 49, 64, 81]


List Comprehensive


set1 = [1, 2, 3] set2 = [3, 1, 4]


List Comprehensive


set1 = [1, 2, 3] set2 = [3, 1, 4]

combs = [] for x in set1: for y in set2: if x != y: comb.append((x, y))


List Comprehensive


set1 = [1, 2, 3] set2 = [3, 1, 4]

combs = [(x, y) for x in set1 for y in set2 if x != y] [(1, 3), (1, 4), (2, 3), (2, 1), (2, 4), (3, 1), (3, 4)]


Working with File

Working with Fileopen('filename', mode)

# r: open file for read# w: open file for write# a: open file for append



f = open('data.txt', r)f.read() # read file to stringf.readline() # read file for one linef.readlines() # read file to lines



f = open('data.txt', r)f.read() # read file to stringf.readline() # read file for one linef.readlines() # read file to lines

f.write('this is a cat') # write string to filef.writelines([list of line]) # write lines to file

Object Oriented Programming

Object Oriented ProgrammingClass

Object Oriented ProgrammingClass

Instance

Object Oriented Programmingclass Book: def __init__(self, name, size): self.name = name self.size = size class BookStack: def __init__(self): self.books = [] self.top = 0 def push(self, book): self.books.append(book) self.top += 1 def pop(self): self.top -= 1 return self.books.pop() !

Test Driven Development

Unit Testimport unittest !class TestBookStack(unittest.TestCase): # when book is created, it can return name, size def test_book_created(self): hunger_book = Book('The Hunger Games', 4) self.assertEqual(hunger_book.name, 'The Hunger Games') self.assertEqual(hunger_book.size, 4) # when Book Stack is created / top is 0 def test_book_stack_created(self): book_stack = BookStack() self.assertEqual(book_stack.top, 0) self.assertEqual(book_stack.books, []) # when push book / top increase by one def test_book_stack_push(self): hunger_book = Book('The Hunger Games', 4) book_stack = BookStack() book_stack.push(hunger_book) self.assertEqual(book_stack.top, 1) self.assertEqual(book_stack.books[0].name, 'The Hunger Games') book_stack.push(hunger_book) self.assertEqual(book_stack.top, 2) # when pop book / top decrease by one def test_book_stack_pop(self): hunger_book = Book('The Hunger Games', 4) harry_book = Book('Harry Potter', 3) book_stack = BookStack() book_stack.push(hunger_book) book_stack.push(harry_book) present_size = book_stack.top poped_book = book_stack.pop() self.assertEqual(book_stack.top, present_size - 1) self.assertEqual(poped_book.name, 'Harry Potter') if __name__ == '__main__': unittest.main()


Problem#3: Books

Instruction:!! - Using TDD!!! - Each Book have a name, size!! - Books have size and all of book!!Test case:!! - paste the new book on top!! - pick a book at top of books!! - when paste new book you must take a larger book to below!! - program can tell a present Books size

Migrate to Python 3

❖ print is function instead of statement!

❖ input()!❖ range instead of xrange!❖ more usage on lazy generator

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