Pemrograman Python untuk Pemula

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

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

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

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

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/

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

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

Python Brochure | http://getpython.info

Introduction to Python with Jessica McKellar

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

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

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

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

Indentation
4-space indents and no hard tab character

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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)

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

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

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

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

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

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

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

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

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

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

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

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)

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

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

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()))

main.py (cont’d)
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)

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>

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

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

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:
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

main.py ...snip...
import models
...snip...
def get(self):
current_time = datetime.datetime.now()
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)

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>

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)

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

Pemrograman Python untuk Pemula

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