This document provides an introduction to programming with Python for beginners. It covers basic Python concepts like variables, data types, operators, conditional statements, functions, loops, strings and lists. It also demonstrates how to build simple web applications using Google App Engine and Python, including templating with Jinja2, storing data in the Datastore and handling web forms. The goal is to teach the fundamentals of Python programming and get started with cloud development on Google Cloud Platform.

1. Pemrograman dengan
Python untuk Pemula
oon arfiandwi
http://oo.or.id/py

2. Material ini digunakan untuk kelas teknologi pengenalan pemrograman
dengan bahasa pengantar Python http://oo.or.id/py
Dipublikasikan dengan lisensi Atribusi-Berbagi Serupa
Creative Commons (CC BY-SA) oleh oon@oo.or.id

3. Tools to Install
Download Python 2.7 from http://python.org/download
or you can easly use online Python interpreter
For Google Cloud Platform topic:
Google App Engine SDK for Python from https:
//cloud.google.com/appengine/downloads
Pip Python Package Manager from http://pip.pypa.
io/en/latest/installing.html

4. Outline
Python intro
Type, Variable, Value
Functions
Conditional
Iteration
String processing
Intro to Google Cloud Platform with Python

5. Reference
http://www.greenteapress.com/thinkpython/
http://www.pythonlearn.com/
http://www.diveintopython.net/
https://www.python.org/download/
http://pythoncentral.org/comparison-of-python-ides-
development/

6. Software/Program/App
compiled or interpreted (or both)
input-process-output (decide input & output, think about the process)
syntax and semantic
>>> 1 + 2 = 3
>>> panjang = 3
>>> lebar = 4
>>> luas = panjang + lebar

7. Python
➔ High-level language
➔ Interactive mode & Scripting mode
➔ Online interpreter
◆ http://www.skulpt.org/
◆ http://pythontutor.com/
➔ case sensitive

8. Python Brochure | http://getpython.info

9. Introduction to Python with Jessica McKellar

10. Hello Python
>>> print ‘Hello, World!’
Hello, World!
>>> type(‘Hello, World!’)
<type ‘str’>
>>> print 1+2
3
>>> type(3)
<type ‘int’>
>>> type(‘1’)

11. Type, Variable, Value
>>> i = 1
(i adalah variable, dengan type int, memiliki value 1, diberi nilai dengan operator =)
>>> kata = ‘nilai’
(kata adalah variable, dengan type str, memiliki value nilai)
some of basic data type:
Integer: int
String: str
Boolean: bool

12. Variable Assignment
>>> message=’message in the bottle’
>>> print message
>>> type(message)
>>> x=1
>>> x=x+2
>>> x+=3
>>> y=4
>>> print x*y

13. Operator & Operand
1+2
(1 adalah operand, + adalah operator, 2 adalah operand)
x < xx and z > y
(operand? operator?)
Order of operations: PEMDAS

14. Indentation
4-space indents and no hard tab character

15. Interactive Mode & Scripting Mode
give sample of interactive mode on console
give sample of scripting mode count_down.py

16. List
List is a sequence, of elements or items
[1, 2, 3]
['ab', 'bc', 'cd', 'de']
['ab', 'bc', 1, 2, 1.1, [True, False]]

17. Array
array.array is a wrapper of C arrays. can
handle only homogeneous C array of data.
so for common use, simply use List
http://stackoverflow.
com/questions/176011/python-list-vs-array-when-
to-use

18. Tuple
>>> t = (1, 2, 3)
>>> type(t)
<type ‘tuple’>
>>> print t
>>> t = (‘hello’)
>>> print t

19. String
String as sequence
String slice
String methods (intro OO first)
String comparison
in Operator

20. String
>>> kata = ‘pemrograman’
>>> print kata[4]
>>> lenkata = len(kata)
>>> print lenkata
>>> print kata[lenkata-1]
>>> for char in kata:
… print char
>>> print kata.upper()

21. String Operations
Concatenation
>>> print ‘pemrograman’ + ‘python’

22. Formatted Printing
print 'formatting %s %d' % ('text', 7)
http://forums.udacity.
com/questions/2019688/python-101-unit-2-
formatted-printing-and-function-documentation

23. Conditional
if
if .. else ..
if .. elif .. else ..

24. Conditional sample
>>> hari = ‘minggu’
>>> if hari == ‘sabtu’ or hari == ‘minggu’:
… print ‘akhir pekan!’
…
akhir pekan!

25. boolean, and, or
x and y
akan bernilai True, jika keduanya True
selain itu bernilai False
x or y
akan bernilai False, jika keduanya False
selain itu bernilai True

26. Conditional samples (2)
>>> x = 4
>>> if x%2 == 0:
… print ‘even’
… else:
… print ‘odd’

27. assignments
buat kode program untuk mengecek apakah
variable x itu positif atau negatif
>>> x = -1
buat kode program untuk mengecek apakah
variable x itu positif, negatif, atau nol
>>> x = 0

28. Conditional samples (3)
>>> x = 7
>>> if x > 8:
… print ‘A’
… elif x>6 and x<8:
… print ‘B’
… else:
… print ‘C’

29. Functions
Function call
Add new functions
Fruitful function, void function
import
importing with from

30. function call and create function
>>> type(True)
>>> def apakah_genap(angka):
… if angka%2 == 0:
… print ‘benar, genap’
… else:
… print ‘salah, ganjil’
>>> apakah_genap(7)
>>> apakah_genap(100)

31. function call and create function
>>> def luas_persegi(panjang, lebar):
… luas = panjang * lebar
… return luas
…
>>> luasnya = luas_persegi(20, 30)
>>> print luasnya

32. import function
>>> import math
>>> print math
>>> akar9 = math.sqrt(9)
>>> print akar9

33. assignment
buat sebuah fungsi luas_lingkaran
>>> luas_lingkaran(10)
note:
pi: math.pi
input: jari-jari
process: pi * jari-jari * jari-jari

34. Iteration with while
>>> x = 7
>>> while x>0:
… print ‘data-%i’ % x
… x = x -1

35. assignment
buat iteration menggunakan while, dalam
sebuah fungsi, yang akan menampilkan hanya
angka yang genap saja.
>>> count_down_genap(4)
4
2

36. Iteration while with break
>>> while not ketemu:
... databerikut = cari_data()
... if databerikut == yangdicari:
... break
...

37. Iteration with for
>>> for i in range(3)
… print ‘ulang’
>>> for i in range(5,10)
… print i

38. comments & docstring
>>> xxx = 3 # var name xxx
>>> print xxx

39. Variable Scope
local

40. Google Cloud Platform with Python
let’s start by making a website using python
Google Cloud Platform have a free tier of
Google App Engine
we’ll develop using Google App Engine SDK for
Python
https://developers.google.com/appengine/docs/python/gettingstartedpython27/introduction

41. Google App Engine SDK for Python
create 2 files on directory
app.yaml
main.py
dev_appserver.py projectdir
open http://localhost:8080/

42. app.yaml
application: waktusaatini
version: 1
runtime: python27
api_version: 1
threadsafe: true
handlers:
- url: .*
script: main.application
libraries:
- name: webapp2
version: latest

43. main.py
import datetime
import webapp2
class MainPage(webapp2.RequestHandler):
def get(self):
message = ‘<p>waktu %s</p>’ % datetime.datetime.now()
self.response.out.write(message);
application = webapp2.WSGIApplication([(‘/’, MainPage)], debug=True)

44. Template Engine Jinja2
install Jinja2
# pip install jinja2
3 Files:
● app.yaml
● main.py
● home.html
Upload to appspot:
# appcfg.py update kelas-teknologi/
Sample: http://kelas-teknologi.appspot.com

45. app.yaml
application: kelas-teknologi
version: 1
runtime: python27
api_version: 1
threadsafe: true
handlers:
- url: .*
script: main.application
libraries:
- name: webapp2
version: latest
- name: jinja2
version: latest
- name: markupsafe
version: latest

46. main.py
import datetime
import webapp2
import jinja2
import os
from google.appengine.api import users
template_env = jinja2.Environment(
loader=jinja2.FileSystemLoader(os.getcwd()))

47. main.py (cont’d)
class MainPage(webapp2.RequestHandler):
def get(self):
current_time = datetime.datetime.now()
user = users.get_current_user()
login_url = users.create_login_url(self.request.path)
logout_url = users.create_logout_url(self.request.path)
template = template_env.get_template('home.html')
context = {
'current_time': current_time,
'user': user,
'login_url': login_url,
'logout_url': logout_url,
}
self.response.out.write(template.render(context))
application = webapp2.WSGIApplication([('/', MainPage)], debug=True)

48. home.html
<html><head><title>The Time Is...</title></head>
<body>
{% if user %}
<p>
Welcome, <strong>{{ user.email() }}</strong>!
You can <a href="{{ logout_url }}">sign out</a>.
</p>
{% else %}
<p> Welcome!
<a href="{{ login_url }}">Sign in or register</a> to customize. </p>
{% endif %}
<p>The time is: {{ current_time }}</p>
</body></html>

49. Web Form & Datastore
5 Files:
● app.yaml
● models.py
● main.py
● prefs.py
● home.html
Upload to appspot:
# appcfg.py update kelas-teknologi/
Sample: http://kelas-teknologi.appspot.com

50. app.yaml
application: kelas-teknologi
version: 1
runtime: python27
api_version: 1
threadsafe: true
handlers:
- url: /prefs
script: prefs.application
login: required
- url: .*
script: main.application
libraries:
- name: webapp2
version: latest
- name: jinja2
version: latest
- name: markupsafe
version: latest

51. models.py from google.appengine.api import users
from google.appengine.ext import db
class UserPrefs(db.Model):
tz_offset = db.IntegerProperty(default=0)
user = db.UserProperty(auto_current_user_add=True)
def get_userprefs(user_id=None):
if not user_id:
user = users.get_current_user()
if not user:
return None
user_id = user.user_id()
key = db.Key.from_path('UserPrefs', user_id)
userprefs = db.get(key)
if not userprefs:
userprefs = UserPrefs(key_name=user_id)
return userprefs

52. main.py ...snip...
import models
...snip...
class MainPage(webapp2.RequestHandler):
def get(self):
current_time = datetime.datetime.now()
user = users.get_current_user()
userprefs = models.get_userprefs()
if userprefs:
current_time += datetime.timedelta(0, 0, 0, 0, 0, userprefs.tz_offset)
...snip...
context = {
'current_time': current_time,
'user': user,
'login_url': login_url,
'logout_url': logout_url,
'userprefs': userprefs,
}
self.response.out.write(template.render(context))
application = webapp2.WSGIApplication([('/', MainPage)], debug=True)

53. home.html <html><head><title>The Time Is...</title></head>
<body>
{% if user %}
<p>
Welcome, <strong>{{ user.email() }}</strong>!
You can <a href="{{ logout_url }}">sign out</a>.
</p>
{% else %}
<p> Welcome!
<a href="{{ login_url }}">Sign in or register</a> to customize. </p>
{% endif %}
{% if user %}
<form action="/prefs" method="post">
<label for="tz_offset">
Timezone offset from UTC (can be negative):
</label>
<input name="tz_offset" id="tz_offset" type="text"
size="4" value="{{ userprefs.tz_offset }}" /> <input type="submit" value="Set" />
</form>
{% endif %}
<p>The time is: {{ current_time }}</p>
</body></html>

54. prefs.py import webapp2
import models
class PrefsPage(webapp2.RequestHandler):
def post(self):
userprefs = models.get_userprefs()
try:
tz_offset = int(self.request.get('tz_offset'))
userprefs.tz_offset = tz_offset
userprefs.put()
except ValueError:
# User entered a value that wasn't an integer. Ignore for now.
pass
self.redirect('/')
application = webapp2.WSGIApplication([('/prefs', PrefsPage)],
debug=True)

55. OO: Type - Class
None

56. Sample with Flask
None

57. Oon Arfiandwi
Co-founder of 7Langit mobile agency
http://oo.or.id/py
http://google.com/+oonarfiandwi
http://twitter.com/oonid
http://about.me/oon