Python !" @henocdz 

Why Python? Just trust me, you will love it! @henocdz 

Windows user? No problem. Use Ac#ve Python for Installa-on @henocdz 

Data Types # Numbers a_integer = 2623 # Up to sys.int_info * a_float = 69.89 # Up to sys.float_info * #Booleans of_horse = True nope = False # Binary as_bytes = b'A random text stored as bytes' # Nothing my_money = None @henocdz 

Data Types # Sequences a_string = 'Python is Awesome!' # Are immutable! a_string_quotes = "Python is love!" a_string_triple = '''Python is life!''' a_list = [1, [2], 1, a_string, 3.67] # Any size, any data type a_tuple = (5, ['z'], 89, ) # Same rules of lists apply, but this are immutable a_tuple_comma = 5, ['z'], 89, # Comma is the element separator a_set = set([1, 1, 4, 1]) # =[1,4] Collection with no duplicate elements @henocdz 

Data Types # Dictionaries a_dict = { # Key can be any immutable object # (i.e, numbers, strings, tuples) 'some_key': 'some value', 4: 'another value', a_tuple: a_list # Can be a key only if the tuple contains immutable objects } @henocdz 

Operators @henocdz 

Arithme(c Operators # Addition (+) >>> result = 4 + 10 14 # Subtraction (-) >>> 2014 - 2015 1 # Multiplication (*) >>> 2 * 10 20 @henocdz 

Arithme(c Operators (cont) # Division (/) >>> 10 / 2 5.0 # Type Float # Floor Division (//) >>> 10 // 2 5 # Type Integer # Modulus (%) >>> 14 % 2 # Exponent (**) >>> 2 ** 2 4 @henocdz 

Comparison Operators # Evaluates if two elements are equal >>> 10 == 10 True # Evaluates if two elements are not equal >>> 10 != 5 True # Evaulates if the value of left operand is greater than the value of right operand >>> 14 < 2 False # Viceversa >>> 14 > 2 True # >= and <= are also supported @henocdz 

Assignment Operators >>> something = 'classic' # You can combine any arithmetic operator with (=) operator # like this :) >>> something *= 3 'classicclassicclassic' @henocdz 

Membership Operators >>> 5 in [3, 4, 10] False >>> 5 not in [3, 4, 10] True @henocdz 

Control Flow Tools @henocdz 

Condi&onal Statements IF-ELSE some_bool = True # if-else structure >>> if some_bool: ... print('Some bool it\'s True!!') >>> else: ... print('Some bool it\'s not True :(') @henocdz 

IF-ELSE-IF >>> alumni = True >>> senseis = False >>> if alumni and senseis: ... print('We are ready!') >>> elif alumni: ... print('Waiting for senseis...') >>> elif senseis: ... print('Waiting for alumni...') >>> else: ... print('Fuck!') @henocdz 

INLINE IF-ELSE >>> ready = True if alumni and senseis else False @henocdz 

FOR # Iterates over a sequence # (list, tuple, string, bytes, bytesarray, etc.) >>> senseis = ('Henoc', 'Gus', 'Sergio', ) >>> for sensei in senseis: ... print(sensei) Henoc Gus Sergio @henocdz 

COMMON FOR # range(5) > [0, 1, 2, 3, 4] # range(4, 5) > [4] >>> for i in range(0, 5): ... print(i) 0 1 2 3 4 @henocdz 

WHILE # Tests the expression and, if it is true, executes the block; # if the expression is false the loop terminates >>> im_awesome = True >>> while im_awesome: ... stay_awesome() @henocdz 

BREAK & CONTINUE You can control a loop with 1. break: terminates the loop 2. con)nue: ignore the rest of the block and returns to evaluate the expression >>> while True: ... if im_tired: ... break @henocdz 

Func%ons >>> def tellme_the_truth(): ... print('May the force be with You!') >>> def function_with_params(a_param): ... print(a_param) >>> def function_default_values(a_param, has_default=True): ... """Params with no default value must be defined first""" ... print(a_param, has_default) >>> def give_me_the_year(): ... return 2015 @henocdz 

Lambda Func+ons >>> do_something = lambda a_number: a_number * a_number >>> do_something(14) 196 @henocdz 

Execu&ng Func&ons >>> tellme_the_truth() May the force be with You! >>> function_with_params('A string!') A string! >>> function_default_values('not a number') not a number, True >>> function_default_values('a number', False) a number, False >>> function_default_values('default', has_default=False) default, False >>> give_me_the_year() 2015 @henocdz 

I/O Communica)on with real users @henocdz 

Input / Output >>> user_input = input('Tell me your name: ') Tell me your name: [[Henoc]] >>> print(user_input, type(user_input)) Henoc @henocdz 

! @henocdz 

And now what? ! @henocdz 

Running Python Script File Create a file and edit it with your favorite code editor: $ touch file_name.py $ vim file_name.py # Run the file $ python file_name.py @henocdz 

Style guides For example: Don't use Cammel Case with func3on or variables, instead you must use snake case i.e, def thiIsWrong(): def this_is_ok(): 1. PEP8 a. h)ps:/ /www.python.org/dev/peps/pep-0008/ 2. Google Style Guide b. h)p:/ /google.github.io/styleguide/pyguide.html @henocdz 

Exercises @henocdz 

[1] List Overlap Take two lists, say for example these two: a = [1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89] b = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13] Then write a program that returns a list that contains only the elements that are common between the lists (without duplicates). Make sure your program works on two lists of different sizes. @henocdz 

[2] Cows and bulls Create a program that will play the “cows and bulls” game with the user. The game works like this: Randomly generate a 4-digit number. Ask the user to guess a 4-digit number. For every digit that the user guessed correctly in the correct place, they have a “cow”. For every digit the user guessed correctly in the wrong place is a “bull.” Every Ame the user makes a guess, tell them how many “cows” and “bulls” they have. Once the user guesses the correct number, the game is over. Keep track of the number of guesses the user makes throughout teh game and tell the user at the end. Say the number generated by the computer is 1038. An example interacAon could look like this: Welcome to the Cows and Bulls Game! Enter a number: 1234 2 cows, 0 bulls 1256 1 cow, 1 bull Un#l the user guesses the number. @henocdz 

Hints You can use random module to generate pseudo-random numbers For example: >>> import random >>> random.randint(1000, 9999) 8756 @henocdz 

Extra Exercises • [1] Randomly generate two lists to test this @henocdz 

Packages and Modules ! @henocdz 

Modules A file that contains python defini1ons like func1ons, classes or variables So, almost any file it's a module, for example: # File name: my_math.py def zum(a, b): return a + b def pow(a, b): return a ** b @henocdz 

We can import a module in other modules like this # File name: other_file.py >>> import my_math >>> print(my_math.zum(3, 4)) 7 # Just one definition with >>> from my_math import zum >>> print(zum(1, 2)) 2 # Single definition with an alias >>> from my_math import zum as my_sum >>> print(my_zum(12, 12)) 24 @henocdz 

Script file vs Module If you pass your module name to the interpreter, this is executed as script file, so everything in the module file will be executed as-is. If you don't want that, we can use global variable __name__ for code that should be executed only in script mode; like this: if __name__ = '__main__': print('Running as script file...') Global variable __name__ contains the name of the module, but if the module is executed as an script, this variable contains the string __main__ @henocdz 

Packages A folder that contains other packages or module files utils/ __init__.py my_math.py ... my_script.py Use __init__.py file to convert a folder into a package @henocdz 

And then we can import some module from the u"ls package like this: # import definition >>> from utils.my_math import zum >>> zum(a, b) # import module >>> from utils import my_math >>> my_math.zum() @henocdz 

! Let's rock @henocdz 

Object Oriented Programming @henocdz 

Classes Basic class Student(object): """The Doc string, used for documenting our class""" # Class attributes skills = [] def __init__(self, belt, skills): # self points to the current instance self.belt = belt self.skills = skills def get_skills(self): # self is required return self.skills @henocdz 

Crea%ng instances You can create objects or instances like this # New instance >>> dany = Student( ... belt='Red', ... skills=['Python', 'Javascript'] ... ) @henocdz 

Calling methods >>> dany.get_skills() ['Python', 'Javascript'] @henocdz 

Accessing a*ributes # Anyone have access to all attributes of a class or object >>> dany.skills ['Python', 'Javascript'] >>> dany.belt 'Red' # We can modify class attributes >>> Student.skills [] @henocdz 

Inheritance class A(object): def some_method(self): print('something') class B(A): def some_method(self): print('I\'m the class `B :)') super(B, self).some_method() # Basic Inheritance is from left to right class C(A, B): pass Super-pro algorithm for inheritance: h4ps://www.python.org/download/releases/2.3/mro/ @henocdz 

Magic Methods Like __init__ You can use this magic methods to override operators behavior, i.e., class Student(object): ... def __add__(self, other): if isinstance(other, self.__class__): skills = self.get_skills() + other.get_skills() belt = self.belt + other.belt return Student(belt, skills) @henocdz 

Other magic methods: @henocdz 

String forma,ng The correct way for concatena.on and prin.ng strings combined with other object types # Simple way "I like to {}".format('code') # Simple way 2 "I {1} to {0}".format('code', 'like') # 'Complex' way "I {verb} to {what}".format(what='code', verb='like') @henocdz 

Exercise h"ps:/ /github.com/comunidad-devf/PythonExercises/tree/master/ Classes01 @henocdz 

Virtual Environment Isolated Python environments Imagine that you have two applica3ons and both depends on MyPackage, but the first one requires version 1 of MyPackage and the later one requires version 2 of MyPackage. The solu)on for that is a virtual environment. In Python 3 you can do so with this command: # pyvenv command it's installed when you install Python3 $ pyvenv ENV_DIR ENV_DIR is the folder where our virtualenv will be installed. @henocdz 

Older versions For older versions of python i.e <2.7.x you must install virtualenv package in order to work with Virtual Environments and the create it, like this: # Install virtualenv package $ pip install virtualenv # Create a virtualenv $ virtualenv ENV_DIR @henocdz 

! @henocdz