[헷갈린다] Python Class

|  Object Oriented Programming

 

Class : blueprint for objects (Everything is object in Python)

 

attributes = state of an object (variables)

methods = behavior of an object (functions)

 

 

|  Create Class

 

Class is Templates, and we need something to refer data of a particular object

Self is a stand-in for a particular object 

Should me the first argument of any method

 

 

class MyCounter:
    def set_count(self, n):
        self.count = n
mc = MyCounter()
mc.set_count(5)
mc.count = mc.count + 1
print(mc.count)

 

class Employee:
    pass

emp = Employee()

 

class Employee:

    def set_name(self, new_name):     
        self.name = new_name               <-name이라는 명령어를 부르면 이렇게 변경하겠다

emp = Employee ()
emp.set_name('Korel Rossi')
print(emp.name)

 

 

class Employee:
    def set_name(self, new_name):
        self.name = new_name
    def set_salary(self, new_salary):
        self.salary = new_salary
    def give_raise(self, amount):
        self.salary = self.salary + amount
    def monthly_salary(self):
        return self.salary / 12

emp = Employee()
emp.set_name('Korel Rossi')
emp.set_salary(50000)

mon_sal = emp.monthly_salary()
print(mon_sal)

 

 

__init__ method (Constructor) : called every time an.object is created

: set the default value for the attributes

 

 

|  속성(Attribute) 생성하는 2가지 방법

1. using the methods 

 

2. define altogether using constructor (__init__)

 

 

Class 직접 짜보기

 

# Write the class Point as outlined in the instructions

import numpy as np

import math as mt

class Point:

    def __init__(self,x=0.0,y=0.0):

        self.x = x

        self.y = y

 

def distance_to_origin(self):

    return np.sqrt(self.x**2 + self.y**2)

def reflect(self,axis):

    self.axis = axis

     if axis == "x":

        self.y = -self.y

     elif axis == "y":

        self.x = -self.x

     else:

        print("error!")

pt = Point(x=3.0)

pt.reflect("y")

print((pt.x, pt.y))

pt.y = 4.0

print(pt.distance_to_origin())