Concepts for Python

Python is a high-level, interpreted programming language known for its simplicity, readability, and versatility. Created by Guido van Rossum and first released in 1991, Python emphasizes code readability and productivity, with a clear and concise syntax that favors readability and reduces the cost of program maintenance. Python supports multiple programming paradigms, including procedural, object-oriented, and functional programming styles. Key features include dynamic typing, automatic memory management (garbage collection), extensive standard libraries, and a vibrant ecosystem of third-party packages through the Python Package Index (PyPI). Python is widely used in various domains such as web development, data science, artificial intelligence, scientific computing, and automation, making it one of the most popular and widely adopted programming languages today.

• Print Text

  print('Hello World!')
  print("Hello World!")

• Comments

  # one line comment
  
  """
  multi 
  line 
  comment
  """

• Variables

  carCount = 2
  name = 'Joe'
  isPurple = true

• Data Types

  carCount = 2
  age = 15
  seaLevel = -10000
  usBudget = 11000000000
  lightSpeed = 11799312874
  myGPA = 3.45
  piValue = 3.14159265
  lastLetter = 'Z'
  isMale = true
  myName = 'Joe'

• Math Op

  carCount = 6;
  truckCount = 3;
  
  total = carCount + truckCount;
  print(total);
  
  subtract = carCount - truckCount;
  print(subtract);
  
  multiple = carCount * truckCount;
  print(multiple);
  
  divisible = carCount / truckCount;
  print(divisible);
  
  #  performs division and gets remainder which is 0
  modulo = carCount % truckCount;
  print(modulo);

• Math Functions

  import math
  from random import randint
  
  power = math.pow(3, 6);
  print(power);
  
  root = math.sqrt(16);
  print(root);
  
  floorVal = math.floor(3.14);
  print(floorVal);
  
  ceilVal = math.ceil(4.3);
  print(ceilVal);
  
  roundVal = round(3.4);
  print(roundVal);
  
  # random number from 0 to 100
  ranNum = randint(0, 100)
  print(ranNum) 

• If/Else

  carCount = 6
  
  if carCount > 3:
    print("More than three cars")
  elif:
    print("Equal to three cars")
  else:
    print("Less than or equal to three cars")

• Ternary

  carCount = 3
  
  result = "Yes" if carCount > 2 else "No"
  print(result)

• Switch

  carCount = 3
  
  match carCount: 
    case 1:
      print("One car")
    case 2:
      print("Two cars")
    case 3:
      print("Three cars")
    case _:
      print("More than three")

• Functions

  def handleCars(cars, wheels):
    total =  cars * wheels
    return total
  
  result = handleCars(3, 4)
  print(result)

• Interpolation

  name = 'Joe'
  car = 'Mazda'
  result = f"{name} drives a {car}"
  print(result)

• Type Casting

  def squareA(length):
    result = length ** 2
    return str(result)
   
  squareL = "4"
  convertedVal = int(squareL)
  area = squareA(convertedVal)
  print(area)

• Date and Time

  import datetime
  
  # current date and time
  today = datetime.datetime.now()
  print(today)
  
  #setup date time instance
  strDate = datetime.datetime(2023, 11, 20)
  
  # Full numeric month 
  month = strDate.strftime("%m")
  
  # get word version of month
  strMonth = strDate.strftime("%B")
  
  # grabs day from date obj
  day = strDate.strftime("%d")
  
  # grabs year form date obj
  year = strDate.strftime("%Y")
  
  # concatenate to produce a full date 
  fullDate = f"{month}/{day}/{year}" 
  strFull = f"{strMonth} {day}, {year}"
  
  print(year)
  print(fullDate)
  print(strFull)

• Classes

  class Cars:
    def __init__ (self):
      self.carList = []
      
    def addCar(self, name):
      self.carList.append(name)
   
    def removeFirst(self):
      self.carList.pop(0)
  
    def getFirstVal(self):
      if len(self.carList) > 0:
        return self.carList[0]
      return '';
  
  newList = Cars()
  newList.addCar('Honda')
  newList.addCar('Mazda')
  newList.addCar('Toyota')
  newList.removeFirst()
  firstCar = newList.getFirstVal()
  print(firstCar)

• Inheritance

  class User:
    def __init__ (self, username, password):
      self.username = username
      self.password = password
      
  class Admin(User):
    def __init__ (self, id, password, username):
      super().__init__(username, password)
      self.id = id
    def getUsername(self):
      return f"{self.username}"
    def getAdminID(self):
      return self.id
      
  newAdmin = Admin('alpha 0', 'pw1', '1FE')
  print(newAdmin.getUsername())
  print(newAdmin.getAdminID())

• Method Overload

  // No Native Support or Implementation
  

• Abstract Class

  from abc import ABC, abstractmethod 
  
  class Animation (ABC):
    @abstractmethod
    def walk(self):
      pass
    @abstractmethod
    def run(self):
      pass
    @abstractmethod
    def idle(self):
      pass
  
  class Human(Animation):
    def walk(self):
      print('Human walks')
    def run(self):
      print('Human runs')
    def idle(self):
      print('Human idles')
  
  class Zombie(Animation):
    def walk(self):
      print('Zombie walks')
    def run(self):
      print('Zombie runs')
    def idle(self):
      print('Zombie idles')
    
  player = Human()
  player.walk()
  
  zombie = Zombie()
  zombie.run()

• Static Class

  class Helper:
    @staticmethod
    def circleA(radius):
      return (3.14 * (radius ** 2))
    
    @staticmethod
    def squareA(length):
      return length ** 2
      
  circle = Helper.circleA(3)
  print(circle)
  
  square = Helper.squareA(4)
  print(square)

• Arrays/Lists

  names = ["Joe", "Alex", "Bob"]
  names[1] = "Tom"
  name = names[1]
  numItems = len(names)
  
  print(name)
  print(numItems)

• Array Methods

  cars = ['Honda', 'Mazda', 'Toyota']
  
  // number of elements
  initLength = len(cars)
  print(initLength)
  
  // removes element at index one
  cars.pop(1)
  print(cars[1])
  
  // adds element at end
  cars.append('Tesla')
  print(cars[2])
  
  // removes element with Tesla
  cars.remove('Tesla')
  print(len(cars))
  
  // reverses current order of elements
  cars.reverse()
  print(cars)

• Concatenation

  import numpy as n
  
  carsListKr = ['Kia', 'Hyundai', 'Daewoo']
  carsListJp = ['Honda', 'Mazda', 'Toyota']
  combined = n.concatenate([carsListKr, carsListJp])
  
  print(combined[1])
  print(combined[4])

• Sort Method

  ages = [5, 3, 1, 6, 7, 4, 19]
  ages.sort()
  print(ages)

• Objects

  class User:
    def __init__(
      self, 
      first,
      last,
      age,
      retired,
      carBrands,
    ):
      self.first = first
      self.last = last
      self.age = age
      self.retired = retired
      self.carBrands = carBrands
    def fullName(self):
      return f"{self.first} {self.last}"
  
  carBrands = ["Mazda", "Toyota"];
  user = User(
              "Joe",
              "Doe",
              23,
              False,
              carBrands
            )
  
  print(user.first)
  print(user.carBrands[1])
  print(user.fullName())

• Maps (Key/Value)

  carMap = {}
  carMap["Joe"] = "Toyota"
  carMap["Bob"] = "Mazda"
  carMap["Tom"] = "Ford"
  
  print(carMap.get("Tom"))
  
  carMap.pop("Tom")
  print(carMap.keys())

• Sets

  cars = set();
  
  cars.add('Mazda')
  cars.add('Toyota')
  cars.add('Honda')
  
  print('Honda' in cars)
  
  cars.remove('Honda')
  print('Honda' in cars)

• Stack

  cars = []
  
  cars.append('Mazda')
  cars.append('Toyota')
  cars.append('Honda')
  
  print(cars[len(cars) - 1])
  
  cars.pop(len(cars) - 1);
  print(cars[len(cars) - 1])

• Queues

  cars = []
  
  cars.append('Mazda')
  cars.append('Toyota')
  cars.append('Honda')
  
  print(cars[0])
  
  cars.pop(0)
  print(cars[0])

• Linked List

  class Node:
    def __init__(self, value):
      self.value = value
      self.next = None
  
  class LinkedList:
    def __init__(self):
      self.head = None
      
    def add(self, value):
      newNode = Node(value)
      if self.head == None:
        self.head = newNode
      else:
        current = self.head
        while(current.next):
          current = current.next
        current.next = newNode
        
    def returnHead(self):
      return self.head.value
      
    def traverse(self):
      current = self.head
      while(current):
        print(current.value)
        current = current.next
  
  carList = LinkedList()
  carList.add('Mazda')
  carList.add('Toyota')
  carList.add('Honda')
  
  print(carList.returnHead())
  carList.traverse()

• Graphs

  class Graph:
    def __init__(self):
      self.graphMap = {}
      
    def addNode(self, val):
      self.graphMap[val] = []
      
    def addVertices(self, node1, node2):
      if node1 not in self.graphMap:
          self.graphMap[node1] = []
      if node2 not in self.graphMap:
          self.graphMap[node2] = []
  
      self.graphMap[node1].append(node2)
      self.graphMap[node2].append(node1)
  
    def breadthTraverse(self, start):
      queue = [start]
      visited = {}
      visited[start] = True
      
      while(len(queue) > 0):
        val = queue[0]
        print(val)
  
        queue.pop(0)
        tempArr = self.graphMap[val]
  
        for i in tempArr:
          if i not in visited:
            queue.append(i)
            visited[i] = True
           
    def depthTraverse(self, start):
      stack = [start]
      visited = {}
      visited[start] = True
      
      while(len(stack) > 0):
        val = stack[len(stack) - 1]
        print(val)
  
        stack.pop(len(stack) - 1)
        tempArr = self.graphMap[val]
  
        for i in tempArr:
          if i not in visited:
            stack.append(i)
            visited[i] = True
            
  newGraph = Graph()
  newGraph.addNode('a');
  newGraph.addVertices('a', 'b');
  newGraph.addVertices('a', 'c');
  newGraph.addVertices('b', 'd');
  newGraph.addVertices('b', 'e');
  newGraph.addVertices('d', 'f');
  newGraph.addVertices('d', 'g');
  newGraph.addVertices('d', 'h');
  newGraph.addVertices('e', 'i');
  newGraph.addVertices('e', 'j');
  newGraph.breadthTraverse("a");
  newGraph.depthTraverse("a");

• For Loops

  names = ['Joe', 'Alex', 'Bob']
  
  for name in names:
    print(name)

• While Loops

  carList = ['Mazda', 'Toyota', 'Honda']
  
  while(len(carList) > 0):
    print(carList[0])
    carList.pop(0)
   
  print(len(carList))

• Loop Breaks

  cars = ['Toyota', 'Honda', 'Mazda']
  
  for index, car in enumerate(cars):
    if car == 'Honda':
      print(f"Found at index {index}")
      break
    print(f"Visited index {index}")

• Recursion

  def getSum(arr):
    if len(arr) == 0:
      return 0
    firstVal = arr[0]
    arr.pop(0)
    return firstVal + getSum(arr)
  
  testArr = [1, 2, 4, 5]
  sum = getSum(testArr)
  print(sum)

• Regex Words

  import re
  
  pattern = '\w+'
  phrase = 'I am legend'
  result = re.search(pattern, phrase)
  
  print(result[0])

• Regex Numbers

  import re
  
  pattern = '\d+'
  phrase = 'I am 23'
  result = re.search(pattern, phrase)
  
  print(result[0])

• Regex Test

  import re
  
  name = 'Bob Lee'
  pattern = 'Lee'
  result = bool(re.search(pattern, name))
  
  print(result)

• Regex Characters

  import re
  
  pattern = '#+\w?'
  phrase = '##I am legend##'
  result = re.search(pattern, phrase)
  
  print(result[0])