python►b-OOP

Python-b04-Special(Magic/Dunder) Methods

This article shows the examples of special(magic/dunder) methods in python

basic

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class Employee:
    raise_amount = 2.04

    def __init__(self, first, last, pay):
        self.first = first
        self.last = last
        self.pay = pay
        self.email = first + '.' + last + '@company.com'

    def fullname(self):
        return '{} {}'.format(self.first, self.last)

    def apply_raise(self):
        self.pay = int(self.pay * self.raise_amount)

    def set_regular_raise_amount(self, amount):
        self.raise_amount = amount

    @classmethod
    def set_class_raise_amount(cls, amount):
        cls.raise_amount = amount

    @staticmethod
    def is_workday(day):
        if day.weekday() == 5 or day.weekday() == 6:
            return False
        return True

emp_1 = Employee('Bob', 'Gobdo', 20)
print(emp_1)                # <__main__.Employee object at 0x00000200249F63A0>

__repr__ method is used for debug

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    class Employee:
    raise_amount = 2.04

    def __init__(self, first, last, pay):
        self.first = first
        self.last = last
        self.pay = pay
        self.email = first + '.' + last + '@company.com'

    def fullname(self):
        return '{} {}'.format(self.first, self.last)

    def apply_raise(self):
        self.pay = int(self.pay * self.raise_amount)

    def set_regular_raise_amount(self, amount):
        self.raise_amount = amount

    @classmethod
    def set_class_raise_amount(cls, amount):
        cls.raise_amount = amount

    @staticmethod
    def is_workday(day):
        if day.weekday() == 5 or day.weekday() == 6:
            return False
        return True
        
    def __repr__(self):
        return "Employee('{}','{}',{})".format(self.first, self.last, self.pay)

emp_1 = Employee('Bob', 'Gobdo', 20)
print(emp_1)        #Employee('Bob','Gobdo',20)

__str__ method is used for user

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class Employee:
    raise_amount = 2.04

    def __init__(self, first, last, pay):
        self.first = first
        self.last = last
        self.pay = pay
        self.email = first + '.' + last + '@company.com'

    def fullname(self):
        return '{} {}'.format(self.first, self.last)

    def apply_raise(self):
        self.pay = int(self.pay * self.raise_amount)

    def set_regular_raise_amount(self, amount):
        self.raise_amount = amount

    @classmethod
    def set_class_raise_amount(cls, amount):
        cls.raise_amount = amount

    @staticmethod
    def is_workday(day):
        if day.weekday() == 5 or day.weekday() == 6:
            return False
        return True

    def __repr__(self):
        return "Employee('{}','{}',{})".format(self.first, self.last, self.pay)

    def __str__(self):
        return '{} - {}'.format(self.fullname(), self.email)
    
emp_1 = Employee('Bob', 'Gobdo', 20)
print(emp_1)                # Bob Gobdo - Bob.Gobdo@company.com

print(emp_1.__repr__())     # Employee('Bob','Gobdo',20)

__add__ method

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class Employee:
    raise_amount = 2.04

    def __init__(self, first, last, pay):
        self.first = first
        self.last = last
        self.pay = pay
        self.email = first + '.' + last + '@company.com'

    def fullname(self):
        return '{} {}'.format(self.first, self.last)

    def apply_raise(self):
        self.pay = int(self.pay * self.raise_amount)

    def set_regular_raise_amount(self, amount):
        self.raise_amount = amount

    @classmethod
    def set_class_raise_amount(cls, amount):
        cls.raise_amount = amount

    @staticmethod
    def is_workday(day):
        if day.weekday() == 5 or day.weekday() == 6:
            return False
        return True

    def __repr__(self):
        return "Employee('{}','{}',{})".format(self.first, self.last, self.pay)

    def __str__(self):
        return '{} - {}'.format(self.fullname(), self.email)

    def __add__(self, other):
        return self.pay + other.pay

emp_1 = Employee('Bob', 'Gobdo', 20)
emp_2 = Employee('John', 'Youhs', 30)
print(emp_1 + emp_2)            # 50

__len__ method

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class Employee:
    raise_amount = 2.04

    def __init__(self, first, last, pay):
        self.first = first
        self.last = last
        self.pay = pay
        self.email = first + '.' + last + '@company.com'

    def fullname(self):
        return '{} {}'.format(self.first, self.last)

    def apply_raise(self):
        self.pay = int(self.pay * self.raise_amount)

    def set_regular_raise_amount(self, amount):
        self.raise_amount = amount

    @classmethod
    def set_class_raise_amount(cls, amount):
        cls.raise_amount = amount

    @staticmethod
    def is_workday(day):
        if day.weekday() == 5 or day.weekday() == 6:
            return False
        return True

    def __repr__(self):
        return "Employee('{}','{}',{})".format(self.first, self.last, self.pay)

    def __str__(self):
        return '{} - {}'.format(self.fullname(), self.email)

    def __add__(self, other):
        return self.pay + other.pay

    def __len__(self):
        return len(self.fullname())

emp_1 = Employee('Bob', 'Gobdo', 20)
print(len(emp_1))       # 9

python►b-OOP

Python-b03-Inheritance

This article shows the examples of inheritance in python

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# Developer is a sub class of Employee
class Employee:
raise_amount = 2.04

    def __init__(self, first, last, pay):
        self.first = first
        self.last = last
        self.pay = pay
        self.email = first + '.' + last + '@company.com'

    def fullname(self):
        return '{} {}'.format(self.first, self.last)

    def apply_raise(self):
        self.pay = int(self.pay * self.raise_amount)

    def set_regular_raise_amount(self, amount):
        self.raise_amount = amount

    @classmethod
    def set_class_raise_amount(cls, amount):
        cls.raise_amount = amount

    @staticmethod
    def is_workday(day):
        if day.weekday() == 5 or day.weekday() == 6:
            return False
        return True

class Developer(Employee):
pass

emp_1 = Developer('Bob', 'Gobdo', 20)
emp_2 = Developer('John', 'Youhs', 30)

print(emp_1.email)      # Bob.Gobdo@company.com
print(emp_2.email)      # John.Youhs@company.com

print(help(Developer))


# change variable in sub class
class Developer(Employee):
    raise_amount = 3

emp_1 = Employee('Bob', 'Gobdo', 20)

print(emp_1.pay)        # 20
emp_1.apply_raise()
print(emp_1.pay)        # 40


dev_1 = Developer('Bob', 'Gobdo', 20)

print(emp_1.pay)        # 20
emp_1.apply_raise()
print(emp_1.pay)        # 60

# inherit __init__
class Developer(Employee):
    raise_amount = 3

    def __init__(self, first, last, pay, prog_lang):
        super().__init__(first, last, pay)
        self.prog_lang = prog_lang


dev_1 = Developer('Bob', 'Gobdo', 20, 'Python')
print(dev_1.email)          # Bob.Gobdo@company.com
print(dev_1.prog_lang)      # Python


# another sub class
class Developer(Employee):
    raise_amount = 3

    def __init__(self, first, last, pay, prog_lang):
        super().__init__(first, last, pay)
        self.prog_lang = prog_lang

class Manager(Employee):

    def __init__(self, first, last, pay, employees = None):
        super().__init__(first, last, pay)
        if employees is None:
            self.employees = []
        else:
            self.employees = employees

    def add_employee(self, emp):
        if emp not in self.employees:
            self.employees.append(emp)

    def remove_employee(self, emp):
        if emp in self.employees:
            self.employees.remove(emp)

    def print_emps(self):
        for emp in self.employees:
            print('-->', emp.fullname())

dev_1 = Developer('Bob', 'Gobdo', 20, 'Python')

mgr_1 = Manager('Sue', 'Smith', 50, [dev_1])
print(mgr_1.email)              # Sue.Smith@company.com
mgr_1.print_emps()              # --> Bob Gobdo

dev_2 = Developer('John', 'Youhs', 30, 'Java')
mgr_1.add_employee(dev_2)
mgr_1.print_emps()              # --> Bob Gobdo
                                # --> John Youhs

mgr_1.remove_employee(dev_2)
mgr_1.print_emps()             # --> Bob Gobdo

# isinstance, issubclass

print(isinstance(mgr_1, Manager))   # True
print(isinstance(mgr_1, Employee))  # True
print(isinstance(mgr_1, Developer)) # False

print(issubclass(Developer, Employee))  # True
print(issubclass(Manager, Employee))    # True
print(issubclass(Manager, Developer))   # False
python►b-OOP

Python-b02-classmethod-staticmethod

This article shows the examples of classmethod and staticmethod in python

regular method

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class Employee:
    raise_amount = 2.04

    def __init__(self, first, last, pay):
        self.first = first
        self.last = last
        self.pay = pay
        self.email = first + '.' + last + '@company.com'

    def fullname(self):
        return '{} {}'.format(self.first, self.last)

    def apply_raise(self):
        self.pay = int(self.pay * self.raise_amount)

    def set_regular_raise_amount(self, amount):
        self.raise_amount = amount


emp_1 = Employee('Bob', 'Gobdo', 20)
emp_2 = Employee('John', 'Youh', 30)

emp_1.set_regular_raise_amount(6)

print(emp_1.raise_amount)       # 6
print(emp_2.raise_amount)       # 2.04
print(Employee.raise_amount)    # 2.04
```  
## classmethod

class Employee:
raise_amount = 2.04

def __init__(self, first, last, pay):
    self.first = first
    self.last = last
    self.pay = pay
    self.email = first + '.' + last + '@company.com'

def fullname(self):
    return '{} {}'.format(self.first, self.last)

def apply_raise(self):
    self.pay = int(self.pay * self.raise_amount)

def set_regular_raise_amount(self, amount):
    self.raise_amount = amount

@classmethod
def set_class_raise_amount(cls, amount):
    cls.raise_amount = amount

emp_1 = Employee(‘Bob’, ‘Gobdo’, 20)
emp_2 = Employee(‘John’, ‘Youh’, 30)

Employee.set_class_raise_amount(5)

print(emp_1.raise_amount) # 5
print(emp_2.raise_amount) # 5
print(Employee.raise_amount) # 5

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## staticmethod

class Employee:
raise_amount = 2.04

def __init__(self, first, last, pay):
    self.first = first
    self.last = last
    self.pay = pay
    self.email = first + '.' + last + '@company.com'

def fullname(self):
    return '{} {}'.format(self.first, self.last)

def apply_raise(self):
    self.pay = int(self.pay * self.raise_amount)

def set_regular_raise_amount(self, amount):
    self.raise_amount = amount

@classmethod
def set_class_raise_amount(cls, amount):
    cls.raise_amount = amount

@staticmethod
def is_workday(day):
    if day.weekday() == 5 or day.weekday() == 6:
        return False
    return True

import datetime
my_date = datetime.date(2016,1,2)
print(Employee.is_workday(my_date)) # False

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## example

class A(object):
bar = 1

def func1(self):
    print('foo')

@classmethod
def func2(cls):
    print('func2')
    print(cls.bar)
    cls().func1()

@staticmethod
def func3():
    print('func3')
    print(A.bar)

A().func1() # foo
A.func2() # func2
# 1
# foo
A.func3() # func3
# 1

```

python►b-OOP

Python-b01-Classes and Instances

This article shows the examples of Classes and Instances in python

OOP: Object-Oriented Programming

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# basic
class Employee:
    def __init__(self, first, last, pay):
        self.first = first
        self.last = last
        self.pay = pay
        self.email = first + '.' + last + '@company.com'

    def fullname(self):
        return '{} {}'.format(self.first, self.last)


emp_1 = Employee('Bob', 'Gobdo', 20)
print(emp_1.email)
print(emp_1.fullname())

# the same thing of fullname()
print(Employee.fullname(emp_1))

# class variables
class Employee:
    raise_amount = 2.04

    def __init__(self, first, last, pay):
        self.first = first
        self.last = last
        self.pay = pay
        self.email = first + '.' + last + '@company.com'

    def fullname(self):
        return '{} {}'.format(self.first, self.last)

    def apply_raise(self):
        self.pay = int(self.pay * self.raise_amount) # raise_amount is class vriable, we can remplace by Employee.raise_amount


emp_1 = Employee('Bob', 'Gobdo', 20)
print(emp_1.pay)        # 20
emp_1.apply_raise()
print(emp_1.pay)        # 40

print(Employee.__dict__)    # there is raise_amount inside
print(emp_1.__dict__)       # there is no raise_amount inside


# change raise_amount by instance
emp_1 = Employee('Bob', 'Gobdo', 20)
emp_2 = Employee('John', 'Youhs', 30)

emp_1.raise_amount = 3
print(Employee.raise_amount)    # 2.04
print(emp_1.raise_amount)       # 3
print(emp_2.raise_amount)       # 2.04

# change raise_amount by class
emp_1 = Employee('Bob', 'Gobdo', 20)
emp_2 = Employee('John', 'Youhs', 30)

Employee.raise_amount = 3
print(Employee.raise_amount)    # 3
print(emp_1.raise_amount)       # 3
print(emp_2.raise_amount)       # 3

python►a-basics

Python-a09-Modules

This article shows the examples of Modules in python

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## my_module.py file
    print('Imported my_module...')
    
    test = 'Test String'
    
    def find_index(to_search, target):
        '''Find the index of a value in a sequence'''
        for i, value in enumerate(to_search):
            if value == target:
                return i
        return -1
    
## test.py basic
    import my_module

    courses = ['History', 'Math', 'Physics', 'CompSci']
    
    index = my_module.find_index(courses, 'Math')
    
    print(index)   # Imported my_module...
                   # 1   
                    
## test.py as
    import my_module as mm

    courses = ['History', 'Math', 'Physics', 'CompSci']
    
    index = mm.find_index(courses, 'Math')
    
    print(index)   # Imported my_module...
                   # 1
    
## test.py from
    from my_module import find_index,test
    
    courses = ['History', 'Math', 'Physics', 'CompSci']
    
    index = find_index(courses, 'Math')
    
    print(index)       # Imported my_module...
                       # 1
    print(test)        # Test String
     
## test.py from as
    from my_module import find_index as fi,test
    
    courses = ['History', 'Math', 'Physics', 'CompSci']
    
    index = fi(courses, 'Math')
    
    print(index)       # Imported my_module...
                       # 1
    print(test)        # Test String
 
## sys.path: the path of modules to import from
     
    from my_module import find_index, test
    import sys
    
    courses = ['History', 'Math', 'Physics', 'CompSci']
    
    index = find_index(courses, 'Math')
     
    # print(index)
    # print(test)
    print(sys.path) # ['C:\\Dev\\examples\\python\\python_examples',...]
    
## add path to sys.path or to PYTHONPATH
    # move my_module.py to new dir mymoduledir
    # rerun test.py, there is an error ModuleNotFoundError
    
    # solution 1: add mymoduledir to sys.path
        import sys
        sys.path.append('C:\Dev\examples\python\python_examples\mymoduledir')
        print(sys.path)   
         
    # solution 2: set mymoduledir to PYTHONPATH
        set PYTHONPATH=C:\Dev\examples\python\python_examples\mymoduledir
        
## import existing libraries
    # random
    import random
    courses = ['History', 'Math', 'Physics', 'CompSci']
    random_choice = random.choice(courses)
    print(random_choice)
    
    # math
    import math
    res = math.log2(2)
    print(res)    # 1.0
    
    # datetime
    import datetime
    
    today = datetime.date.today()
    print(today)
    
    # os
    import os
    # get current working directory
    print(os.getcwd())

python►a-basics

Python-a08 Functions

This article shows the examples of Functions in python

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## basic
    def hello_func():
        pass

    print(hello_func)  # <function hello_func at 0x000001FC6BA4C430>
    print(hello_func())  # None

## function without input
    def hello_func():
        return 'hello'
    print(hello_func())             # hello

## function with input
    def hello_func(greeting):
        return '{} Function.'.format(greeting)
    print(hello_func('Hi'))         # Hi Function.

## default value
    def hello_func(greeting, name='You'):
        return '{}, {} Function.'.format(greeting, name)

    print(hello_func('Hi'))         # Hi, You Function.
    
## positional arguments, keyword arguments
   ## 1
    def student_info(*args, **kwargs):
        print(args)
        print(kwargs)

    student_info('Math', 'Art', name='John', age=22)    # ('Math', 'Art')
                                                        # {'name': 'John', 'age': 22}
    
   ## 2    
    courses = ['Math', 'Art']
    info = {'name': 'John', 'age': 22}
    student_info(courses, info)         # (['Math', 'Art'], {'name': 'John', 'age': 22})
                                        # {}     
                                        
   ## 3    
    courses = ['Math', 'Art']
    info = {'name': 'John', 'age': 22}
    student_info(*courses, **info)         # ('Math', 'Art')
                                           # {'name': 'John', 'age': 22}
                                                                                 
## example print number of month days 
    month_days = [0,31,28,31,30,31,30,31,31,30,31,30,31]

    def is_leap(year):
        """Return True for leap years, False for non-leap years."""

        return (year % 4 == 0 and year % 100 != 0) or year % 400 == 0


    def days_in_month(year, month):
        """Return number of days in that month in that year."""
    
        if not 1 <= month <= 12:
            return 'Invalid Month'
    
        if month == 2 and is_leap(year):
            return 29
    
        return month_days[month]
    
    print(days_in_month(2020,2))    # 29
    print(days_in_month(2021,2))    # 28
python►a-basics

Python-a07 Loops and Iterations

This article shows the examples of Loops and Iterations in python

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## loop
    nums = [1,2,3,4,5]
    for num in nums:
        print(num, end="; ")          # 1; 2; 3; 4; 5
        
## break
    nums = [1,2,3,4,5]
    for num in nums:
        if num == 3:
            print('Found !', end="; ")
            break
        print(num, end="; ")      # 1; 2; Found !
        
## continue
    nums = [1,2,3,4,5]
    for num in nums:
        if num == 3:
            print('Found !', end="; ")
        continue
        print(num, end="; ")      # 1; 2; Found !; 4; 5;
        
## loop within loop
    nums = [1,2,3]
    for num in nums:
        for letter in 'abc':
            print(num, letter, end="; ")     # 1 a; 1 b; 1 c; 2 a; 2 b; 2 c; 3 a; 3 b; 3 c; 
            
## range
    for num in range(1, 11):
        print(num, end="; ")     # 1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 
        
## while
    x = 0
    while x < 10:
        print(x, end="; ")
        x+=1                      # 0; 1; 2; 3; 4; 5; 6; 7; 8; 9;
devops►terraform

Terraform-a01-Introduction

What is Terraform

Terraform is a tool for building, changing, and versioning infrastructure safely and efficiently.
It is open source and declarative

The differences between declarative and imperative:
declarative: define WHAT the result you want
imperative: define exact steps - HOW

The key features:

  • Infrastructure as Code
  • Execution Plan
  • Resource Graph
  • Change Automation

A. Previsioning infrastructure:

  1. private network space
  2. ec2 server instances
  3. install Docker and other tools
  4. security

B. Deploy applications

Difference between Ansible and Terraform

Both: Infrastructure as a Code

Ansible

Better for configuring that infrastructure

Mainly a configuration tool
More mature

Terraform

Better for infrastructure

Mainly infrastructure provisioning tool
More advanced in orchestration

How does Terraform work

  1. create execution plan

  2. execute plan with providers

Configuration

example:

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terraform {
  required_providers {
    google = {
      source = "hashicorp/google"
      version = "3.5.0"
    }
  }
}

provider "google" {

  credentials = file("<NAME>.json")

  project = "<PROJECT_ID>"
  region  = "us-central1"
  zone    = "us-central1-c"
}

resource "google_compute_network" "vpc_network" {
  name = "terraform-network"
}

Terraform Block

it defines which provider to download from Terraform Registry

Provider

It is used to configure the named provider

Resource

It contains the resource type, and the resource name.

resource ID: resource type and resource name together

Commands

refresh:
query provider to get the current state

plan:
create an execution plan

apply:
execute the plan

destroy:
destroy the resources/infrastructure

python►a-basics

Python-a06-Conditions and Boolean

This article shows the examples of Conditions and Boolean in python

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## basic
    if True:
        print('Conditional was true') # Conditional was true
        
    if False:
        print('Conditional was true') #
       
# Comparisons
    # Equal:            ==
    # Not Equal:        !=
    # Greater Than:     >
    # Less Than:        <
    # Greater or Equal: >=
    # Less or Equal:    <=
    # Object Identity:  is
    
    language = 'Python'
    if language == 'Python':
        print('Conditional was true') # Conditional was true
    else:
        print('No match') 
        
    num = [1,2,3]
    num_two = [1,2,3]
    num_three = num
    print(num is num_two) # False
    print(num is num_three) # True
    print(id(num))
    print(id(num_two))
    
    
# if elif else        
    language = 'Python'
    if language == 'Python':
        print('Conditional was true')
    elif language == 'Java':
        print('Language is Java')    
    else:
        print('No match') 

# booleans operators: and or not
    user = 'Admin'
    logged_in = True
    
    if user == 'Admin' and logged_in:
        print('Admin Page')
    else:
        print('Bad')
            
            
    if user == 'Admin' or logged_in:
        print('Admin Page')
    else:
        print('Bad')      
          
              
    if not logged_in:
        print('Please Log in')
    else:
        print('Welcome')
        
# False Values:
    # False
    # None
    # 0 of any numeric type
    # Any empty sequence, for example: '', (), []
    # Any empty mapping, for example: {}
    
    condition = False
    if condition:
        print('Evaluated to True')
    else:
        print('Evaluated to False')
python►a-basics

Python-a05-Dictionaries

This article shows the examples of Dictionaries in python

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## basic
    student =  {'name': 'John', 'age': 25, 'courses': ['Math', 'CompSci']}
    print(student) # {'name': 'John', 'age': 25, 'courses': ['Math', 'CompSci']}
    print(student['name']) # John
    print(student['courses'][0]) # Math
    print(student['phone']) # error
    
    print(student.get('name')) # John
    print(student.get('phone')) # None
    print(student.get('phone', 'Not Found')) # Not Found
    
# add and update element
    student['phone'] = '555'    
    student['name'] = 'Bob'
    print(student) # {'name': 'Bob', 'phone': '555', 'age': 25, 'courses': ['Math', 'CompSci']}
    
    student.update({'name': 'Jane', 'age': 26, 'phone': '666'})
    print(student) # {'name': 'Jane', 'phone': '666', 'age': 26, 'courses': ['Math', 'CompSci']}

# delete element
    student =  {'name': 'John', 'age': 25, 'courses': ['Math', 'CompSci']}
    del student['age']
    print(student) # {'name': 'John', 'courses': ['Math', 'CompSci']}

    age = student.pop('age')
    print(student) # {'name': 'John', 'courses': ['Math', 'CompSci']}
    print(age) # 25
  
# loop
    student =  {'name': 'John', 'age': 25, 'courses': ['Math', 'CompSci']}
    print(student.keys()) # dict_keys(['name', 'age', 'courses'])
    print(student.values()) # dict_values(['John', 25, ['Math', 'CompSci']])
    print(student.items()) # dict_items([('name':'John'), ('age':25), ('courses':['Math', 'CompSci'])])
    
    for key in student:
        print(key) # name; age; courses
        
    for key,value in student.items():
        print(key,value) #name John; age 25; courses ['Math', 'CompSci']