to...

NortHACKton

Why?

•Easy to learn

•Multi paradigm

•Extensive library

•Great community

•Fun!

http://python.org/download/(for now use the 2.7 version)

>>> print "Hello, World!"

“Hello, World!”

“Hello, World!”

$ pythonPython 2.6.1 (r261:67515, Jun 24 2010, 21:47:49) [GCC 4.2.1 (Apple Inc. build 5646)] on darwinType "help", "copyright", "credits" or "license" for more information.>>> print "Hello, World!"Hello, World!

“Hello, World!”

$ pythonPython 2.6.1 (r261:67515, Jun 24 2010, 21:47:49) [GCC 4.2.1 (Apple Inc. build 5646)] on darwinType "help", "copyright", "credits" or "license" for more information.>>> print "Hello, World!"Hello, World!

Start the Python interpreter from the command line

“Hello, World!”

$ pythonPython 2.6.1 (r261:67515, Jun 24 2010, 21:47:49) [GCC 4.2.1 (Apple Inc. build 5646)] on darwinType "help", "copyright", "credits" or "license" for more information.>>> print "Hello, World!"Hello, World! Generic information about the

Python interpreter.

“Hello, World!”

$ pythonPython 2.6.1 (r261:67515, Jun 24 2010, 21:47:49) [GCC 4.2.1 (Apple Inc. build 5646)] on darwinType "help", "copyright", "credits" or "license" for more information.>>> print "Hello, World!"Hello, World!

You type this bit...

“Hello, World!”

$ pythonPython 2.6.1 (r261:67515, Jun 24 2010, 21:47:49) [GCC 4.2.1 (Apple Inc. build 5646)] on darwinType "help", "copyright", "credits" or "license" for more information.>>> print "Hello, World!"Hello, World!

Python returns the result (you made that happen!)

“Hello, World!” function

def hello(name="World!"): """ Makes Python say hello.

:param name: who to greet """ return "Hello, %s" % name

def hello(name="World!"): """ Makes Python say hello.

:param name: who to greet """ return "Hello, %s" % name

Functions are named blocks of code that do stuff.

“Hello, World!” function

def hello(name="World!"): """ Makes Python say hello.

:param name: who to greet """ return "Hello, %s" % name

def = define

“Hello, World!” function

def hello(name="World!"): """ Makes Python say hello.

:param name: who to greet """ return "Hello, %s" % name

hello = name of function

“Hello, World!” function

def hello(name="World!"): """ Makes Python say hello.

:param name: who to greet """ return "Hello, %s" % name

an argument (input) into the function

“Hello, World!” function

def hello(name="World!"): """ Makes Python say hello.

:param name: who to greet """ return "Hello, %s" % name

a default value for the name arg

“Hello, World!” function

def hello(name="World!"): """ Makes Python say hello.

:param name: who to greet """ return "Hello, %s" % name

Whitespace (a 4 space indent) indicates scope

“Hello, World!” function

def hello(name="World!"): """ Makes Python say hello.

:param name: who to greet """ return "Hello, %s" % name

comments& docs

“Hello, World!” function

def hello(name="World!"): """ Makes Python say hello.

:param name: who to greet """ return "Hello, %s" % name

return = result

“Hello, World!” function

def hello(name="World!"): """ Makes Python say hello.

:param name: who to greet """ return "Hello, %s" % name

a string (use either ' or ")

“Hello, World!” function

def hello(name="World!"): """ Makes Python say hello.

:param name: who to greet """ return "Hello, %s" % name

string formatting

“Hello, World!” function

>>> hello()'Hello, World!'>>> hello("NortHACKton")'Hello, NortHACKton'>>> hello("Widget")'Hello, Widget'

Call the function (note the brackets)

>>> hello()'Hello, World!'>>> hello("NortHACKton")'Hello, NortHACKton'>>> hello("Widget")'Hello, Widget'

Here’s the result...

>>> hello()'Hello, World!'>>> hello("NortHACKton")'Hello, NortHACKton'>>> hello("Widget")'Hello, Widget'

Aha! Pass in arguments between the brackets...

HELP!>>> dir()['__builtins__', '__doc__', '__name__', '__package__', 'hello']>>> help(hello)Help on function hello in module __main__:

hello(name='World!') Makes Python say hello. :param name: who to greet

HELP!>>> dir()['__builtins__', '__doc__', '__name__', '__package__', 'hello']>>> help(hello)Help on function hello in module __main__:

hello(name='World!') Makes Python say hello. :param name: who to greet

return the attributes of given scope

display help from docstring

Assignment>>> greeting = hello('NortHACKton!')>>> greeting'Hello, NortHACKton!'>>> type(greeting)<type 'str'>>>> foo = 1>>> type(foo)<type 'int'>>>> bar = 1.234>>> type(bar)<type 'float'>>>> dir(greeting)['__add__', '__class__', '__contains__', '__delattr__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__', '__getslice__', '__gt__', '__hash__', '__init__', '__le__', '__len__', '__lt__', '__mod__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmod__', '__rmul__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '_formatter_field_name_split', '_formatter_parser', 'capitalize', 'center', 'count', 'decode', 'encode', 'endswith', 'expandtabs', 'find', 'format', 'index', 'isalnum', 'isalpha', 'isdigit', 'islower', 'isspace', 'istitle', 'isupper', 'join', 'ljust', 'lower', 'lstrip', 'partition', 'replace', 'rfind', 'rindex', 'rjust', 'rpartition', 'rsplit', 'rstrip', 'split', 'splitlines', 'startswith', 'strip', 'swapcase', 'title', 'translate', 'upper', 'zfill']

Assignment>>> greeting = hello('NortHACKton!')>>> greeting'Hello, NortHACKton!'>>> type(greeting)<type 'str'>>>> foo = 1>>> type(foo)<type 'int'>>>> bar = 1.234>>> type(bar)<type 'float'>>>> dir(greeting)['__add__', '__class__', '__contains__', '__delattr__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__', '__getslice__', '__gt__', '__hash__', '__init__', '__le__', '__len__', '__lt__', '__mod__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmod__', '__rmul__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '_formatter_field_name_split', '_formatter_parser', 'capitalize', 'center', 'count', 'decode', 'encode', 'endswith', 'expandtabs', 'find', 'format', 'index', 'isalnum', 'isalpha', 'isdigit', 'islower', 'isspace', 'istitle', 'isupper', 'join', 'ljust', 'lower', 'lstrip', 'partition', 'replace', 'rfind', 'rindex', 'rjust', 'rpartition', 'rsplit', 'rstrip', 'split', 'splitlines', 'startswith', 'strip', 'swapcase', 'title', 'translate', 'upper', 'zfill']

greeting holds the return value

and it’s a string (of characters)!

Assignment>>> greeting = hello('NortHACKton!')>>> greeting'Hello, NortHACKton!'>>> type(greeting)<type 'str'>>>> foo = 1>>> type(foo)<type 'int'>>>> bar = 1.234>>> type(bar)<type 'float'>>>> dir(greeting)['__add__', '__class__', '__contains__', '__delattr__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__', '__getslice__', '__gt__', '__hash__', '__init__', '__le__', '__len__', '__lt__', '__mod__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmod__', '__rmul__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '_formatter_field_name_split', '_formatter_parser', 'capitalize', 'center', 'count', 'decode', 'encode', 'endswith', 'expandtabs', 'find', 'format', 'index', 'isalnum', 'isalpha', 'isdigit', 'islower', 'isspace', 'istitle', 'isupper', 'join', 'ljust', 'lower', 'lstrip', 'partition', 'replace', 'rfind', 'rindex', 'rjust', 'rpartition', 'rsplit', 'rstrip', 'split', 'splitlines', 'startswith', 'strip', 'swapcase', 'title', 'translate', 'upper', 'zfill']

foo holds the number 1and it’s an integer (whole number)!

Assignment>>> greeting = hello('NortHACKton!')>>> greeting'Hello, NortHACKton!'>>> type(greeting)<type 'str'>>>> foo = 1>>> type(foo)<type 'int'>>>> bar = 1.234>>> type(bar)<type 'float'>>>> dir(greeting)['__add__', '__class__', '__contains__', '__delattr__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__', '__getslice__', '__gt__', '__hash__', '__init__', '__le__', '__len__', '__lt__', '__mod__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmod__', '__rmul__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '_formatter_field_name_split', '_formatter_parser', 'capitalize', 'center', 'count', 'decode', 'encode', 'endswith', 'expandtabs', 'find', 'format', 'index', 'isalnum', 'isalpha', 'isdigit', 'islower', 'isspace', 'istitle', 'isupper', 'join', 'ljust', 'lower', 'lstrip', 'partition', 'replace', 'rfind', 'rindex', 'rjust', 'rpartition', 'rsplit', 'rstrip', 'split', 'splitlines', 'startswith', 'strip', 'swapcase', 'title', 'translate', 'upper', 'zfill']

bar holds the number 1.234and it’s a float (’ing point number)!

Assignment>>> greeting = hello('NortHACKton!')>>> greeting'Hello, NortHACKton!'>>> type(greeting)<type 'str'>>>> foo = 1>>> type(foo)<type 'int'>>>> bar = 1.234>>> type(bar)<type 'float'>>>> dir(greeting)['__add__', '__class__', '__contains__', '__delattr__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__', '__getslice__', '__gt__', '__hash__', '__init__', '__le__', '__len__', '__lt__', '__mod__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmod__', '__rmul__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '_formatter_field_name_split', '_formatter_parser', 'capitalize', 'center', 'count', 'decode', 'encode', 'endswith', 'expandtabs', 'find', 'format', 'index', 'isalnum', 'isalpha', 'isdigit', 'islower', 'isspace', 'istitle', 'isupper', 'join', 'ljust', 'lower', 'lstrip', 'partition', 'replace', 'rfind', 'rindex', 'rjust', 'rpartition', 'rsplit', 'rstrip', 'split', 'splitlines', 'startswith', 'strip', 'swapcase', 'title', 'translate', 'upper', 'zfill']

remember this..?

Assignment>>> greeting = hello('NortHACKton!')>>> greeting'Hello, NortHACKton!'>>> type(greeting)<type 'str'>>>> foo = 1>>> type(foo)<type 'int'>>>> bar = 1.234>>> type(bar)<type 'float'>>>> dir(greeting)['__add__', '__class__', '__contains__', '__delattr__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__', '__getslice__', '__gt__', '__hash__', '__init__', '__le__', '__len__', '__lt__', '__mod__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmod__', '__rmul__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '_formatter_field_name_split', '_formatter_parser', 'capitalize', 'center', 'count', 'decode', 'encode', 'endswith', 'expandtabs', 'find', 'format', 'index', 'isalnum', 'isalpha', 'isdigit', 'islower', 'isspace', 'istitle', 'isupper', 'join', 'ljust', 'lower', 'lstrip', 'partition', 'replace', 'rfind', 'rindex', 'rjust', 'rpartition', 'rsplit', 'rstrip', 'split', 'splitlines', 'startswith', 'strip', 'swapcase', 'title', 'translate', 'upper', 'zfill']

All of the attributes/functions of “greeting”

Program flow...

>>> world_is_flat = False>>> if world_is_flat:... print "The world is flat!"... else:... print "The world is round"... The world is round

Program flow...

>>> world_is_flat = False>>> if world_is_flat:... print "The world is flat!"... else:... print "The world is round"... The world is round

“if” tests for truth

“else” if “if” evaluates to false

The result of this logic...

Program flow...

>>> world_is_flat = False>>> if world_is_flat:... print "The world is flat!"... else:... print "The world is round"... The world is round

NB: there is NO switch in Python. Use elif for further clauses in the logic.

Loops>>> for number in range(10):... print number...

Basically, for each “something” in a group of “somethings” do something

(for each number in a group of numbers print the number)

Loops>>> for number in range(10):... print number... 0123456789

There’s also while

Like many programming languages, Python starts counting from 0 (zero)

>>> my_dictionary = { ... 'key': 'value',... 1: 2,... 'branch': { ... 'leaf': 'node'... }... }>>> my_dictionary['key']'value'>>> my_dictionary[1]2>>> my_dictionary['branch']['leaf']'node'>>> my_dictionary{1: 2, 'branch': {'leaf': 'node'}, 'key': 'value'}

dict = key/value store(think phone book)

get the value from the dict

Why not try dir(my_dictionary)and play.?

Data structurescurly brackets!

Data structures>>> shopping = ['eggs', 'ham', 'spam', 'parrot']>>> len(shopping)4>>> shopping['eggs', 'ham', 'spam', 'parrot']>>> shopping[0]'eggs' >>> shopping[3]'parrot'>>> shopping[4]Traceback (most recent call last): File "<stdin>", line 1, in <module>IndexError: list index out of range>>> shopping[1:]['ham', 'spam', 'parrot']>>> shopping[:1]['eggs']>>> shopping[:-1]['eggs', 'ham', 'spam']>>> shopping[-1:]['parrot']

a list

lists remain in order

get a specific item by position

start counting from zero (remember?)

slicing

square brackets!

import antigravityfrom antigravity import stasisfield

stasisfield.generate()

Modules

OOP(s)

In a nutshell(there’s much more to it than this)

Classes define sorts of things

Objects are instances of classes

Cow = class

Buttercup = object (an instance of cow)

In a nutshell (part 2)(there’s still much more to it than this)

Methods do things (they’re functions)

Attributes define, er, attributes...

Buttercup.breed = “friesian”

Buttercup.moo()Moo!

A very simple view...

Nouns = ClassesProper Nouns = Objects

Verbs = MethodsAdjectives = Attributes

er, sort of... I’m making this up as I go along... :-)

class Cow(object): """ A pythonic cow """

def __init__(self, name="Cow", breed=None): """ Called when the class is instantiated """ self.name = name self.breed = breed

def moo(self, message="MOO!"): """ A bovine hello world! """ return "%s says, %s" % (self.name, message)

Indicates we’re defining a new class...

class Cow(object): """ A pythonic cow """

def __init__(self, name="Cow", breed=None): """ Called when the class is instantiated """ self.name = name self.breed = breed

def moo(self, message="MOO!"): """ A bovine hello world! """ return "%s says, %s" % (self.name, message)

... that we’re calling “Cow”...

class Cow(object): """ A pythonic cow """

def __init__(self, name="Cow", breed=None): """ Called when the class is instantiated """ self.name = name self.breed = breed

def moo(self, message="MOO!"): """ A bovine hello world! """ return "%s says, %s" % (self.name, message)

... that inherits attributes/behaviour from the“object” class.

class Cow(object): """ A pythonic cow """

def __init__(self, name="Cow", breed=None): """ Called when the class is instantiated """ self.name = name self.breed = breed

def moo(self, message="MOO!"): """ A bovine hello world! """ return "%s says, %s" % (self.name, message)

A docstring that explains what this class represents

class Cow(object): """ A pythonic cow """

def __init__(self, name="Cow", breed=None): """ Called when the class is instantiated """ self.name = name self.breed = breed

def moo(self, message="MOO!"): """ A bovine hello world! """ return "%s says, %s" % (self.name, message)

class Cow(object): """ A pythonic cow """

def __init__(self, name="Cow", breed=None): """ Called when the class is instantiated """ self.name = name self.breed = breed

def moo(self, message="MOO!"): """ A bovine hello world! """ return "%s says, %s" % (self.name, message)

A special method

called when a new

object is created with this

class

class Cow(object): """ A pythonic cow """

def __init__(self, name="Cow", breed=None): """ Called when the class is instantiated """ self.name = name self.breed = breed

def moo(self, message="MOO!"): """ A bovine hello world! """ return "%s says, %s" % (self.name, message)

“self” refers to the new object (e.g. Buttercup)

class Cow(object): """ A pythonic cow """

def __init__(self, name="Cow", breed=None): """ Called when the class is instantiated """ self.name = name self.breed = breed

def moo(self, message="MOO!"): """ A bovine hello world! """ return "%s says, %s" % (self.name, message)

self.name and self.breed are attributes of the instantiated object

(Buttercup)

class Cow(object): """ A pythonic cow """

def __init__(self, name="Cow", breed=None): """ Called when the class is instantiated """ self.name = name self.breed = breed

def moo(self, message="MOO!"): """ A bovine hello world! """ return "%s says, %s" % (self.name, message)

A method makes the object do something

>>> from example import Cow>>> buttercup = cow("Buttercup", "friesian")>>> buttercup.name'Buttercup'>>> buttercup.breed'friesian'>>> buttercup.moo()'Buttercup says, MOO!'

http://docs.python.org/tutorial/introduction.html

and now for something completely different...

Your task:Create a Parrot class. It must be able to squawk, flap and, ahem, become deceased. If the parrot is deceased then

calling squawk and flap return the message “This is an ex-parrot”. We should be able to indicate the parrot’s breed

and give it a name. Use your imagination! HAVE FUN!

Show and tell...

End (the)http://python.org/