Introduciton to Python

Creating Big Data:
Introduction to Python
Moshe Kaplan
moshe.kaplan@brightaqua.com

© All rights reserved: Moshe Kaplan
http://top-performance.blogspot.com
Moshe Kaplan
> Scale Hacker:
Architecture (Sys and Data)
R&D
Solving Problems
> Blogs:
http://blogs.microsoft.co.il/vprnd
2

About Me: It’s all About Scale
3

INTRODUCTION
Background
4
http://geekandpoke.typepad.com/geekandpoke/2008/07/one-day-in-the.html

Wny Python?
Simple and readable
Indentation: hard to mess
OOP and functional
Dynamic and auto memory management
Can be packaged
Cross platform
Wide number of libraries
Works great w/ Java, C, .Net
5

Who is Behind?
Python Software Foundation
~1M USD annual budget
Created at 1989
Top 10 from 2008
6
https://en.wikipedia.org/wiki/Python_(programming_language)

Who is Using?
7
http://www.dhruvb.com/blog/images/slides/python/using-python.png

Python Version
2.X  Existing Projects
3.X  New Projects
Not so backwards compatible
8

Materials
9
https://www.tocode.co.il
10% Discount
Coupon Code: PyApplied

IDEs
You can use Notepad++
10

HELLO WORLD
Background
11

12
http://www.dhruvb.com/blog/presentations/python/#/2

13
http://www.dhruvb.com/blog/presentations/python/#/2

VARIABLES, NUMBERS AND
STRINGS
Python
14

C:>Python
Type "help", "copyright", "credits" or "license" for more
information.
>>> a = "hello"
>>> print(a)
hello
>>> print(type(a))
<class 'str'>
>>> a = 1
>>> print(type(a))
<class 'int'>
>>>
Variables
15
Auto Declaration
Auto type assignment

Numbers
Integer (int)
Floating
Complex (a+ib)
16
http://www.slideshare.net/TahaniAlManie/python-3-programming-language

Strings
Immutable (cannot modify)
Char is a single char string
Starts w/ 0 and support –N
17
>>> a = "hello"
>>> a[0]
'h'
>>> a[-1]
'o'

Strings Methods
18

Strings Operators
19

LISTS AND TUPLES
Python
20

Lists Basics
Mutable
Support multi types
Again 0–N
21
>>> l = [1, 'b', 'ccc']
>>> print(l[0])
1
>>> print(l[1:2]);
['b']
>>> l[2] = 3
>>> print(l)
>>> del(l[0])
>>> print(l)
['b', 3]

Lists Magic
Supports list in a list
For each:
22
>>> a = [1, 2, 3]
>>> [x ** 2 for x in a]
[1, 4, 9]

Tuples
Similar functionality to lists
Faster than lists
Perfect for functional programming
23
>>> t = (1, 'b', 'ccc')
>>> t[0] = 2
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment

Dictionaries Basics
Key/Value pairs (JSON like)
Mutable (cannot modify)
24
>>> d = {'name':'moshe', 'course':'PySpark'}
>>> print(d['name'])
moshe
>>> print(d.keys())
dict_keys(['name', 'course'])
>>> print(d.values())
dict_values(['moshe', 'PySpark'])
>>> print(d.items())
dict_items([('name', 'moshe'), ('course', 'PySpark')])

Dictionaries Methods
25

FUNCTIONS
Python
26

Functions Basics
Flexible parameters:
27
>>> def a(name = "moshe", course = "pycourse"):
... print(name + ": " + course)
...
>>> a()
moshe: pycourse
>>> a("roni")
roni: pycourse
>>> a(course = "spark")
moshe: spark

Variable Length Parameters and Refs
Not ByVal and not ByRef:
Mutuable: Object Reference (array)
Immutable: Change pointer each time (string)
28
>>> def f(*tup):
... for t in tup:
... print(t)
...
>>>
>>>
>>> f(1, "b", "ccc")
1
b
ccc
is vs ==

IF STATEMENTS AND LOOPS
Python
29

if
True or False conditions (no null)
Non Null  True
Non Zero  True
30
>>> b = True
>>> if b:
... print(1)
... elif b != True:
... print(2)
... else:
... print(3)
1
>>> x = 'correct' if b == True else 'wrong'

For Loops: Strings
31
>>> for letter in 'python':
... print(letter)
p
y
t
h
o
n

For Loops: For Each
32
>>> for x in range(1, 5):
... print(x)
...
1
2
3
4

While
continue: Well, continue
break: Well, break
pass: Void, due to indentation
33
>>> while (x < 5):
... print(x)
... x = x + 1
0
1
2
3
4

INPUT AND
BASIC TERMINAL APPS
Python
34

Files
f = open(“file_name” [, access_mode] [,buffering])
“r”  read
“w”  recreate
“a”  append
“b”  add for binary reading
i = f.read()  All at once
line = f.readline()  Single line
lines = f.readlines()  All at once to a list
f.write(string)
f.close()
35

I/O
Char is a single char string
Starts w/ 0 and support –N
36
shuffelBlocks = (raw_input("Shuffel Blocks (y/n): ") == 'y')
print(shuffelBlocks)
assert(type(a) == type(1))

CLASSES AND ENTERPRISE
LEVEL PROGRAMMING
Python
37

Classes
38
> Python class.py
Moshe is earning too much
Roni is earning 100
Total Employees: 2
Static variable
Constructor
Object var

Inheritance
By default  Everything public
__attribute  Turn to private
Reflection++:
Multiple inheritance is supported
39
class shape:
...
class Circle(shape):
...

Modules and Imports
Use 3rd party code:
Functions
Classes
Attributes
40
>>> import module1 [, module2]
>>> from module3 import name1 [, name2]
Only specific attributes

Creating Modules
Simple header
And we are done…
41
"""file my_module.py
Module 'my_module': my special module
"""
def my_func(a):
if __name__ == '__main__':
print my_func(1)

Packaging
42
def is_number(s):
try:
int(s)
return True
except ValueError:
return False
if __name__ == '__main__':
COLOR_BREAK = 'blue'
COLOR_HEADER_FOOTER = 'darkCyan';

Python Compiler
See also .pyc file in your stack
43

Python Integration
44

EXCEPTIONS
Python
45

Try and Except
Common:
NameError
TypeError
IndexError
KeyError
46
try:
print(getattr(moshe, "course"))
except NameError:
print("no attribute1")

TESTING
Python
47

How to Do that?
48
import my_module
import unittest
class my_module_test(unittest.TestCase):
def test_method1(self):
self.assertFalse(method1(1))
if __name__ == '__main__':
unittest.main()

PREPARE FOR SPARK
Python
49

Functions are Objects
50
# Evil Code…
>> log, exp = exp, log
>> r = [ -1, 0, 1]
>> map(abs, r)
[1, 0, 1]
>> def sum(x, y): return x+y
>> reduce(sum, r)
0
>> def large(x): return x > 0
>> filter(large, r)
[1]

Thank You !
Moshe Kaplan
moshe.kaplan@brightaqua.com
054-2291978

Introduciton to Python

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