Beginning Python

 This is a workshop, not a talk.
 You are expected to code along.
 So pull out your laptops.
 Install python, ipython and komodo edit. (Or
editor of your choice.)

 Assume that you know programming in any
language.
 So we don’t spend a lot of time explaining
basics.
 BUT, stop and ask if something doesn't make
sense.
 AND Definitely Stop me if I am going too
slow, too fast, or making no sense.

 Dynamically but strongly typed.
 Very object oriented - everything is an object.
 But pragmatic - Objects aren't everthing.
 Allows various paradigms of programming -
OO, procedural, functional.
 Shallow learning curve, but powerful powerful
capabilities available, when you need them.
 import this
 We will come back to this slide.

 Hello world
 >>> print "Hello World"

 for, while, if, else, break, continue
 -Yeah they are available, surprised?
 We will use them in a moment, but after we
see the data structures available.

 List - Like ArrayList in Java
 Tuple - Like List, but immutable
 Dict - Like Hashmaps in Java

 For Loop
 for el in iterable:
 [block statement]
 the classic for loop
 for (int i; i < n; i++){}
 for i in range(n):
 #Work with I
 While condition:
 [block]
 break, continue. Normal operation - break out of
current loop.

 If: elif: else:

 if condition:
 [block]
 else:
 [block]

 You have enough information now to write a
solution
 Problem statement:
 Write a program that prints the numbers from
1 to 100. But for multiples of three print "Fizz"
instead of the number and for the multiples of
five print "Buzz". For numbers which are
multiples of both three and five print
"FizzBuzz".

 def function_name(argument_list):
 [block]
 Functions can have default value.
 def fizzbuzz(till=100, fizz='fizz', buzz='buzz'):
 #fi zzbuzz code
 Functions can have variable length values.
 ex multiply all values passed to a function.
 Functions are first class - They are objects too.
They can be passed to other
 functions, assigned to variables etc.

 class ClassName(base_classes):
 [block]
 Classes are first class too
 They can be passed to function, and assigned
to variables.

 If we list all the natural numbers below 10 that
are multiples of 3 or 5, we get 3, 5, 6 and 9.
The sum of these multiples is 23.
 Find the sum of all the multiples of 3 or 5
below 1000

 The last solution was needlessly verbose
 List comprehension: Take a list and transform it.
 Standard list comprehension syntax - [expr(i) for i
in iterable if condition]
 List of all squares: [i*i for i in range(1,11)]
 List of all squares of even numbers: [i*i for i in
range(1,11) if i%2 == 0]
 So solution to last problem is just
 sum([i*i for i in range(1,1001) if i%3 == 0 or
i%5==0])

 List comprehensions are python way to do
functional programming constructs
 [function(i) for i in iterable if condition] is
filter(func2, map(func1, iter))
 Lets see how this list comprehension maps to
functional concepts
 Get the list of squares of even numbers

 Open a file with - open('location') or
file('location')
 or give a mode - open('location', 'rw')
 iterate as
 for line in open_file.readlines():
 print line #Or whatever
 or
 string = open_file.read()

 Find the most commonly used word in the
Alice in wonderland text.

 Batteries included
 math
 datetime
 string
 re
 random
 os
 pickle
 Do a dir() and see for yourself.
 And a lot, lot more: http://docs.python.org/library/

 Dynamically but strongly typed.
 Very object oriented - everything is an object.
 But pragmatic - Objects aren't everything.
 Allows various paradigms of programming -
OO, procedural, functional.
 Shallow learning curve, but powerful powerful
capabilities available, when you need them.
 import this

 Syntacting sugar for
 foo_func =docorator_func(foo_func)

 Many useful frameworks
 Tornado,
 Pylons,
 Turbogears
 Django
 GAE
 Django: Most actively developed and largest
community participation

 PIL
 Mechanize
 Beautiful Soup
 Element Tree

 python.org
 diveintopython.org
 uswaretech.com/blog

 Thank You.
 You can give feedback, ask questions at
shabda@uswaretech.com

Beginning Python

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