Python入門：5大概念初心者必備 2021/11/18

Python入門：5大概念初心者必備
Derek Lee
2021/11/18

Agenda
你該知道Python的慣例
初探python資料結構
什麼是if-else, for , while
Code能重複用的函式
類別(class)是何物

縮排(Indentation)
 Python 程式碼執行方式：
‘行’為單位
 上下, 左右
 如何管理區塊程式碼(block code)？
 縮排
 優點
 tab或4個space(官方建議)，不建議混用
應用場合：迴圈(for/while)、條件式(if)、函式(function)、類別(class)
def order_meal(meal):
total = 0
while True:
ordered_meal = input('請點餐: ')
if ordered_meal == '':
break
elif ordered_meal in meal:
total = total + meal[ordered_meal]
print(f"{ordered_meal} {meal[ordered_meal]}元, 總金額{total}")
elif ordered_meal not in meal:
print(f'我們沒有提供{ordered_meal}')
print(f"您帳單為{total}元")
meal = {"三明治": 30, "漢堡": 40, "奶茶": 25}
order_meal(meal)

賦值(assignment)
Dynamic assignment
x = 10
print(x)
# 10
# x 參照(reference) 10
x = 10
x = "abc"
x = [1, 2, 3]
print(x)
# [1, 2, 3]
10
“abc”
[1, 2, 3]
x

賦值(assignment)
 變數型別受參照物件的影響
 type(物件)  檢查型別
x = 10
print(type(x))
x = “abc”
print(type(x))
x = [1, 2, 3]
print(type(x))
10
“abc”
[1, 2, 3]
x
<class 'int'>
<class 'str'>
<class 'list'>

賦值(assignment)
 在呼叫前完成assignment
x = 10
print(x + y)
y = 20
# NameError: name 'y' is not defined
x = 10
y = 20
print(x + y)

賦值(assignment)
 每個物件在記憶體都有自己的家
 id() 查記憶體位置
x = 10
print(id(10))
print(id(x))
10
“abc”
[1, 2, 3]
x
1879242816
40148480
40226344

賦值(assignment)
 命名規則
 變數名避開內建(built-in)函式
 導致內建函式無法執行該有的功能
x = 100
print = 19
print(x)
# TypeError: 'int' object is not callable
x = 100
print_ = 19
print(x)
# 100

賦值(assignment)
 命名規則
 第一個字母不能為數字; 可為英文字母或underscore( _ )
 Case Sensitive
3x = 1000
print(3x)
#SyntaxError: invalid syntax
a = "cake"
Print = "cake"
print(a)
# cake

string(字串)
 字元序列(Sequence)
 字元有順序
 資料不可變
 如何建立string？
 如何計算string長度？
x = 'anx'
y = "hsb"
print(type(x), type(y))
# <class 'str'> <class 'str'>
x = "123456"
print(len(x)) # 6

string(字串)
 str() 進行型別轉換
x = 10
print(type(x)) # <class 'int'>
y = str(x)
print(type(y)) # <class 'str'>

string(字串)
數字字串 int() 數字
x = '10'
y = int(x)
print(type(y))
# <class 'int'>
x = 'a'
y = int(x)
print(y)
print(type(y))
#ValueError: invalid literal for int() with base 10: 'a'

string(字串)
 可透過slicing取出特定字元
 無法透過slicing更換字元
x = "hello world"
y = x[0:5]
print(y)
# hello
x = "hello world"
x[0:5] = "wonderful"
print(x)
# TypeError: 'str' object does not support item assignment

string(字串)_常用method
 string.replace(old, new, count)
 new取代old,
 count是指有多少old的字元要被取代(optional, 預設值=all)
 回傳新物件
x = "Hello World"
print(x.replace("l", "99")) # He9999o Wor99d
print(x.replace("l", "99",2)) # He9999o World
print(x) # Hello World

string(字串)_常用method
 字串切割並存成list
 string.split(separator, maxsplit)
 separator：分割符號，預設值為空格
 maxsplit：分割次數；預設值為全部分割
x = "I Love Python and Hello world"
print(x.split()) # ['I', 'Love', 'Python', 'and', 'Hello', 'world']
print(x.split(" ", 2)) # ['I', 'Love', 'Python and Hello world']

string format
可透過 + 或空格串接字串
print("Hello" + " world")
print("Hello " "world")
# Hello world
那如果要串接數個字串或串接時要進行額外處理，改怎做呢?
我們可用兩種string format處理
 string.format
 f-string

string.format
 語法："{},{}".format(v1, v2)
 "{},{}"稱為格式化字串、{}稱為格式化的位置參數
print("{} is the best {} in the {}".format("Python", "language", "world"))
# Python is the best language in the world
位置參數
print("{} * {} = {}".format(2, 3, 2*3))
# 2 * 3 = 6
位置參數指定
print("{0} is the best {1} in the {2}".format("Python", "language", "world"))
# Python is the best language in the world
print("{1} is the best {2} in the {0}".format("Python", "language", "world"))
# language is the best world in the Python

string.format
 語法："{},{}".format(v1, v2)
 "{},{}"稱為格式化字串、{}稱為格式化的位置參數
參數名指定
print("{volum} {fruit}s cost {price} dollars".format(fruit = "apple", price = 100, volum = 10))
# 10 apples cost 100 dollars
同時使用：位置參數在前，參數名指定在後
print("{2} {fruit}s cost {price} dollars".format(fruit = "apple", price = 100, 10))
# SyntaxError: positional argument follows keyword argument
print("{0} {fruit}s cost {price} dollars".format(10, fruit = "apple", price = 100))
# 10 apples cost 100 dollars

f-string
 String Interpolation(字串插值) , 在字串中進行格式化
 語法： f“{x1} {x2}”，其中f大小寫皆可
fruit = "apple"
print(f"My favorite fruit is {fruit}")
# My favorite fruit is apple
 {} 可放入有效的expression
print(f"2*6 is equal to {2*6}") # 2*6 is equal to 12
name = "bob"
print(f"My name is {name.upper()}") # My name is BOB

slicing
 在有序資料中，取出特定的物件。
 有序資料：string, list, tuple
 有序資料的index
 從 0 開始算
0 1 2 3 4 5
-6 -5 -4 -3 -2 -1

slicing
 語法 [start : end : step]
 start: 從哪開始取
 end: 到哪截止(但不包含end)
 step:(optional), 間隔, 如為負數則從最後元素反向取物
x = "HelloPython"
print(len(x)) # 11
print(x[0:10]) # HelloPytho
print(x[0:]) # HelloPython
print(x[1:6:2]) # elP
x = “HelloPython”
print(x[-1: :-1]) # nohtyPolleH
print(x[::-1]) # nohtyPolleH
print(x)

初探Python資料結構
 list
 tuple
 dict
 set

list
 有序資料
 元素可為任意資料型態(type)
 用 []建立
a = [{"a" : 1}, 'b', 1]
print(a)
# [{'a': 1}, 'b', 1]
 用list()進行型別轉換
a = (1, 2, 3, 4, 5) # tuple
print(list(a)) # [1, 2, 3, 4, 5]
b = "12345"
print(list(b)) # ['1', '2', '3', '4', '5']

list
 用len()查詢list元素個數
a = [1, 2, 3, 4, 5]
print(len(a)) # 5
 重複串列所有元素
a = [1, 2, 3, 4, 5]
print(a*3)
# [1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5]

list 常用方法(method)
 用append在串列最後一元素接續新增單一物件
 list.append(element)
a = [] # 空集合
a.append(100)
print(a) # [100]
 大部分method會修改原串列(existing list)
 如用變數接收，結果會是None
b = a.append(100)
print(b) # None

 那麼要如何把串列個別元素新增到c串列中呢？
 list.extend(iterable)
c = [1,2,3]
c.append([99,88,77])
print(c)
猜想的結果 [1, 2, 3, 99, 88, 77]
實際的結果 [1, 2, 3, [99, 88, 77]]
c = [1,2,3]
c.extend([99,88,77])
print(c)
#[1, 2, 3, 99, 88, 77]

 用index查詢物件的位置
 list.index(element)
 用count計算指定物件在串列中出現的次數
 list.count(element)
a = ['a', 'b', 'c', 'd']
print(a.index('c'))
# 2
a = ['a', 'b', 'c', 'd', 'c', 'c', 'c', 'c', 'c', 'c', 'c', 'c', 'c', 'c', 'c']
print(a.count('c'))
# 12

 用sort進行排序
 list.sort(reverse=False, key=func)
1.預設值reverse=False(小到大), reverse=True如要大到小排序
2.key可自訂函式作為排序判斷
a = [1, 3, 4, 7, 2, 5, 9, 0, 11, 6]
a.sort(reverse=False) # 亦可寫 a.sort()
print(a)
# [0, 1, 2, 3, 4, 5, 6, 7, 9, 11]

用join把串列整併形成字串(string)
 ‘ ’.join(iterable); ‘’可放入元素間分隔符號
word_list = ['Hello', 'world']
word_str = ' '.join(word_list)
word_str2 = ' & '.join(word_list)
print(word_str) # Hello world
print(word_str2) # Hello & world

slicing
 用reverse將串列元素進行反轉，未進行排序
 list.reverse()
a = [1, 9, 100, 3, 7, 345]
a.reverse()
print(a) # [345, 7, 3, 100, 9, 1]
 如何用slicing反轉串列的資料呢？
 list[ : : -1]
a = [1, 9, 100, 3, 7, 345]
b = a[::-1]
print(b) # [345, 7, 3, 100, 9, 1]
print(a) # [1, 9, 100, 3, 7, 345]

slicing
我們想複製一份有序資料進行修改，
那該怎麼做呢？
x = [1,2,3,4]
y = x
print(id(x)) # 37998120
print(id(y)) # 37998120
y[0] = 9999
print(y) #[9999, 2, 3, 4]
print(x) #[9999, 2, 3, 4]
複製後修改，如不影響原串列，
那該怎麼做呢？
>> 語法 list[:]
x = [1,2,3,4]
y = x[:]
print(y) # [1, 2, 3, 4]
y[0] = 9999
print(y) # [9999, 2, 3, 4]
print(x) # [1, 2, 3, 4]

tuple
 有序資料但資料不可變
 用()建立
x = () # 空tuple
x = (1, 2, 3, 4)
 如何建立單一個元素的tuple
x = (1)
print(x) # 1 is a int type
我們直覺建立正確：(元素, )
x = (1, )
print(x) # (1, )

tuple with slicing
 slicing僅能讀取資料，不能修改，否則出現TypeError。
x = (1, 2, 3, 4)
print(x[2]) # 3
x = (1, 2, 3, 4)
x[2] = "aaa"
print(x)
# TypeError: 'tuple' object does not support item assignment

tuple 常用方法(method)
 用count計算item出現的次數
 tuple.count(item)
x = (1, 2, 3, 4, 1, 1, 1, 1, 1)
print(x.count(1))
# 6
 用index找出item的位置
 tuple.index(item)
x = (1, 2, 3, 4, 5, "a")
print(x.index("a"))
# 5

dict
 查字典
 {key1: value1, key2: value2}
 key  不可變的物件, 如str, number, tuple
 value  任意物件
 如使用tuple當key, 要確保每個元素都是不可變
x = {1 :'a', 'b' : 2, 'c' : [1,2,3]}
print(x)
# {1: 'a', 'b': 2, 'c': [1, 2, 3]}
y = {([1,2,3], 4, 5):1, 'b':2}
print(y)
# TypeError: unhashable type: 'list'

dict
 資料有重複key，後面key的value取代前面的
z = {'a':1, 'b':2, 'a':"python", 2:'abc', 'a':9999888}
print(z)
# {'a': 9999888, 'b': 2, 2: 'abc'}
 如何在原有dict新增key:value？
 [new_key] = value
z = {'a':1, 'b':2, 'a':"python", 2:'abc', 'a':9999888}
print(z)
z["apple"] = 1094
print(z)
# {'a': 9999888, 'b': 2, 2: 'abc', 'apple': 1094}

dict 常用方法(method)
 dict[key] = value, 除新增key:value, 也可更新key:value
z = {'a': 9999888, 'b': 2, 2: 'abc', 'apple': 1094}
z["a"] = "hello"
print(z)
# {'a': 'hello', 'b': 2, 2: 'abc', 'apple': 1094}
 dict.update(iterable)
z = {'a': 9999888, 'b': 2, 2: 'abc', 'apple': 1094}
z.update({'a': 'hello'})
print(z) # {'a': 'hello', 'b': 2, 2: 'abc', 'apple': 1094}
z.update(({'watch' : 2039}))
print(z) # {'a': 'hello', 'b': 2, 2: 'abc', 'apple': 1094, 'watch': 2039}

 用key取值，語法為dict[key1]，得對應的value1
z = {'a': 9999888, 'b': 2, 2: 'abc', 'apple': 1094}
print(z["apple"]) # 1094
 上述方法取值的缺點: key若不存在, 會產生KeyError
z = {'a': 9999888, 'b': 2, 2: 'abc', 'apple': 1094}
print(z["Apple"]) # KeyError: 'Apple'
 dict.get(key, value=None)
x = {1 :'a', 'b' : 2, 'c' : [1,2,3]}
print(x.get('d')) # None
print(x.get('d', 2)) # 2

 當我們想取用的key:value不在dict，不想出現KeyError,
但希望同步建一組，該怎做？
 dict.setdefault(key,value)
x = {1 :'a', 'b' : 2, 'c' : [1,2,3]}
print(x.setdefault(1,100)) # a
print(x.setdefault('d',"hello world")) # hello world
print(x) # {1: 'a', 'b': 2, 'c': [1, 2, 3], 'd': 'hello world'}

 dict.keys() 取用所有keys
 dict.values() 取用所有values
 dict.items() 取用所有key/value
x = {'a': 199, 'b': "Hello", 'c':[1,2,3]}
print(x.keys())
# dict_keys(['a', 'b', 'c'])
print(x.values())
# dict_values([199, 'Hello', [1, 2, 3]])
print(x.items())
#dict_items([('a', 199), ('b', 'Hello'), ('c', [1, 2, 3])])

set
 無序的資料結構
 元素唯一性
 slicing不適用
 用{}建立
 {} 是空字典; set()是空集合
x = {1, 2, 3, 4}
print(type(x)) # <class 'set'>
x = {1, 1, 1, 1, 1, 1}
print(x) # {1}
x = { }
print(type(x))
# <class 'dict'>
x = {1, 2, 3, 4}
print(x[0])
# TypeError: 'set' object is not subscriptable
x = {1, 2, 3, 4}
x[0] = 2
print(x)
# TypeError: 'set' object does not support item assignment

if-else條件式
 if 條件式成立就執行程式碼,否則就執行else所屬的程式碼
if 條件式成立:
執行code
else:
執行code
x = 100
if x >= 100:
print("數值大於等於100")
else:
print("數值小於100")
# 數值大於等於100

if-else條件式
 elif 多種情況需判別
if 條件式成立:
執行code
elif 條件式成立：
執行code
else:
執行code
age = 10
if age < 0:
print("年齡必須大於0")
elif age > 18:
print("你可以考駕照了")
else :
print("尚未到法定年齡")
# 尚未到法定年齡

while loop
 條件式成立，執行所屬的程式碼，如否，跳出while迴圈
n = 1
nums = []
while n < 5:
nums.append(n)
n += 1
print(nums)
# [1, 2, 3, 4]
while 條件式成立:
執行code

for loop
 概念為item走訪可迭代(iterable)物件，其中可迭代的物件有
string, list, dict, tuple, set等，然後回傳想要的結果。
for item in iterable:
執行code
b = "12345"
print(list(b)) # ['1', '2', '3', '4', '5']
b = "12345"
nums = []
for num in b:
nums.append(num)
print(nums)
# ['1', '2', '3', '4', '5']

range(start, end, step)
 讓item走訪某連續區間的數字
 數值區間會在for迴圈走訪時動態產生
 range(start, end, step)
 start: 預設值為0
 end:執行時被排除
 step:要間隔多少
 搭配list快速產生數值串列
x = range(1, 10)
print(list(x))
# [1, 2, 3, 4, 5, 6, 7, 8, 9]
x = list(range(1, 10, 2))
print(x)
# [1, 3, 5, 7, 9]

for loop
 如何用for loop + range產出一樣的結果？
x = range(1, 10)
print(list(x))
# [1, 2, 3, 4, 5, 6, 7, 8, 9]
nums = []
for num in range(1, 10):
nums.append(num)
print(nums)
#[1, 2, 3, 4, 5, 6, 7, 8, 9]

list comprehension
 語法: [運算式 for 變數 in iterable if 條件成立]
nums = [num for num in range(1, 10)]
print(nums)
# [1, 2, 3, 4, 5, 6, 7, 8, 9]
 簡潔, 可讀性降低
y = [num**2 for num in range(20) if num >10]
print(y)
#[121, 144, 169, 196, 225, 256, 289, 324, 361]
y = []
for num in range(20):
if num > 10:
y.append(num**2)
print(y)
# [121, 144, 169, 196, 225, 256, 289, 324, 361]

break / continue
 break 取消迴圈
 continue 略過後面程式碼，同步進入下一個迴圈
while True:
value = input(“enter integer number (q when exit): ”)
if value == “q” :
break # 離開迴圈
value = int(value)
if value % 2 != 0:
continue #跳過，在進入下一個迴圈
print("the even value is", value)
# 執行結果如下
# enter integer number (q when exit): 1
# enter integer number (q when exit): 2
# the even value is 2
# enter integer number (q when exit): q

有同樣功能該怎做…….?
 ctrl + c / ctrl + v
#設定x, y變數值，印出加總結果
x = 10
y = 20
print(x + y) # 30
#再次設定x, y變數值，印出加總結果
x = 100
y = 299
print(x +y) # 399
如有數個地方使用同功能，難道要一直複製貼上？
如這功能有調整，複製的地方全要同步手動調？

函式(function)
 整併重複使用&功能相同的程式碼
 組成：
 函式名：小寫, _ 連結兩個以上英文字
 參數
 block code
def function_name(parameter,..):
block code
print
function_name()
def function_name(parameter,..):
block code
return
result = function_name()
print(result)

有同樣功能該怎做…….?
 ctrl + c / ctrl + v
#設定x, y變數值，印出加總結果
x = 10
y = 20
print(x + y) # 30
#再次設定x, y變數值，印出加總結果
x = 100
y = 299
print(x +y) # 399
 透過function改寫
def add_value(x, y):
return x + y
result = add_value(10, 20)
print(result)
print(x + y)
add_value(10, 20)

函式(function)
 參數(Parameter)指在定義函數時的形式變數，數值未定
 引述(Argument)呼叫投入的值
print(x + y)
add_value(10, 20)
參數
引數
 定義有參數，呼叫必有引數
return x + y
result = add_value(10)
print(result) # 30
#TypeError: add_value() missing 1 required positional argument: 'y'

函式(function)
 定義有參數，呼叫必有引數
 設定預設值，可避免沒引數造成TypeError
def favorite_food(food = "apple"):
print(f"My favorite food is {food}")
favorite_food("orange")
# My favorite food is orange
favorite_food()
# My favorite food is apple

引數要如何傳遞到函式呢？
 利用參數位置進行傳遞
def subtraction_value(x, y):
return x - y
print(subtraction_value(10, 20)) # -10
print(subtraction_value(20, 10)) # 10
 keyword argument :引數賦予參數名
def subtraction_value(x, y):
return x - y
print(subtraction_value(x = 10, y = 20)) # -10
print(subtraction_value(y = 20, x = 10)) # -10

一個參數對應多個引數
 *args 接收位置參數, 形成tuple
def summation(*args):
return sum(args)
result = summation(1, 2, 3, 4, 5, 6)
print(result) # 21
**kwargs keyword arguments縮寫,形成dict
def kwargs_example(**x):
print(x)
print(type(x))
kwargs_example(a = 1, b = 2, c = "HappyCoding")
# {'a': 1, 'b': 2, 'c': 'HappyCoding'}
# <class 'dict'>

一個參數對應多個引數
def mix_example(x, y, z, w = "defult", *args, **kwargs):
print(x)
print(y)
print(z)
print(w)
print(args)
print(kwargs)
mix_example("apple", 20, [1,2,3], a = 100, greeting = "hello world")
# apple
# 20
# [1, 2, 3]
# defult
# ()
# {'a': 100, 'greeting': 'hello world'}
參數順序:位置參數、預設值、*args、**kwargs

實際案例
 假設餐廳提供三種餐點
 三明治, 50元
 咖啡, 40元
 沙拉, 30元
 寫oder_meal(), 讓使用者輸入餐
點, 統計點餐的總金額, 直到使用
者直接按enter離開
餐點儲存在dict
如使用者輸入菜單上沒有的餐點，
顯示錯誤訊息
使用者點餐結束後,顯示總金額
meal = {"三明治": 50,
"咖啡": 40,
"沙拉": 30
}
def order_meal(meal):
total = 0
while True:
ordered_meal = input('請點餐: ')
if ordered_meal == '':
break
elif ordered_meal in meal:
total = total + meal[ordered_meal]
print(f"{ordered_meal} {meal[ordered_meal]}元, 總金額{total}")
elif ordered_meal not in meal:
print(f'我們沒有提供{ordered_meal}')
print(f"您帳單為{total}元")
# order_meal(meal)
order_meal(meal)
題目來源:Python刷提鍛鍊班

class
 OOP(Object Oriented Programming)
程式碼可再利用(reuse)
易於維護與問題排除(debugging)
針對專案需求進行客製化。
 Python利用類別(class)實現OOP
 Python中所有東西都是物件(object)
 int, list, tuple, string, …….

class
 類別為物件的設計藍圖，同一個類別的物件會有相同的屬性與操作
方法(method)。
class Human:
pass
 屬性(Attribute)：為類別會有的特徵。
 操作方式(Method)：為類別操作的方式，期達到我們想要的結果。
Human
Attribute
Method
姓名, 年齡, 髮色, 身高, …….
走, 跳, 說話, ……..

class
 屬性(Attribute)：為類別會有的特徵。
 操作方式(Method)：為類別操作的方式，期達到我們想要的結果。
class Human:
def __init__(self,name,age): # Method
self.name = name # Attribute
self.age = age
def sound(self, voice):
return f"{self.name} has the {voice} sound"

設定初始值
 使用時機：每個實例物件皆有共同的屬性，以降低冗長的程式碼
 區分同類別的實例化物件，指在實例化過程中給予不同的屬性值，
每個實例物件就會產生差異。
class Human:
def __init__(self,name,age):
self.name = name
self.age = age

實例化(Instantiate)
 從類別物件創造出實例物件的過程
 如何建立實例化物件？
 透過呼叫類別物件、並予以命名。
class Human:
self.name = name
self.age = age
#建立實例化物件
king = Human("king", 22)
queen = Human("Queen", 20)

如何取用類別的屬性與method？
取用屬性：
instance.attribute
取用method：
instance.method()
class Human:
self.name = name
self.age = age
king = Human("king", 22)
queen = Human("Queen", 20)
print(king.name) # King
print(king.age) # 22
print(king.sound("HAHA")) # king has the HAHA sound

如何取用類別的屬性與method？
更改實例物件屬性資料，僅影響自身的屬性值
class Human:
self.name = name
self.age = age
return f“{self.name} has the {voice} sound”
king = Human(“king”, 22)
queen = Human(“Queen”, 20)
queen.name = “Elsa”
queen.age = 21
print(“After changing name is ”, king.name) # After changing name is king
print(“After changing age is ”,king.age) # After changing age is 22
print(“After changing name is ”,queen.name) # After changing name is Elsa
print(“After changing age is ”,queen.age) # After changing age is 21

inheritance
 當你發現寫過類
別的程式碼在新
類別仍然可用，
你會怎麼做？
class Animal:
def __init__(self, name, age):
self.name = name
self.age = age
return voice
d = Animal("Doff", 2)
print("{} is {} years old".format(d.name, d.age)) # Doff is 2 years old
print(d.sound("bark")) # bark
class Dog:
self.name = name
self.age = age
return voice
poppy = Dog("Poppy", 3)
print("{} is {} years old".format(poppy.name, poppy.age)) # Poppy is 3 years old
print(poppy.sound("bark")) # bark
如何解決呢？
繼承(inheritance)

inheritance
 從既有類別(Parent Class)中創造出新的子類別(Child Class),新的子
類別承襲了既有類別的所有屬性與method
class Animal:
self.name = name
self.age = age
return voice
class Dog(Animal):
pass # 雖然無程式碼，但Python仍會執行
poppy = Dog("Poppy", 3)
print("{} is {} years old".format(poppy.name, poppy.age)) #Poppy is 3 years old
print(poppy.sound("bark")) #bark

inheritance
 Child class 如何取用 Parent class的方法(method)？
 super().method
 ParentClass.method
 明確知道取用哪個Parent Class
 缺乏彈性, 當Parent Class改名, 就要逐一修改

inheritance_ super().method
class Animal:
self.name = name
self.age = age
return voice
class Dog(Animal):
def __init__(self, name, age, color):
super().__init__(name,age)
self.color = color
return f"{self.name} has the {voice} sounds"
poppy = Dog("Poppy", 3, "Brown")
print("{} is {} years old and the color is {}".format(poppy.name, poppy.age, poppy.color))
# Poppy is 3 years old and the color is Brown
print(poppy.sound("bark"))
# Poppy has the bark sounds

inheritance_ ParentClass.method
class Animal:
self.name = name
self.age = age
return voice
class Dog(Animal):
Animal.__init__(self, name,age) # 類別名稱後面不用加()、第一個參數須為self
self.color = color
print("{} is {} years old and the color is {}".format(poppy.name, poppy.age, poppy.color))
print(poppy.sound("bark")) # Poppy has the bark sounds

inheritance with Override
 Childe class 與 Parent
class有相同的方法
(method)名，實質內容不
同
class Animal:
self.name = name
self.age = age
return voice
class Dog(Animal):
super().__init__(name,age)
self.color = color
kity = Animal("Kity", 6)
print(f"{poppy.name} is {poppy.age} years old and the color is {poppy.color}")
print(poppy.sound("bark")) # Poppy has the bark sounds
print(kity.sound("Haha....")) # Haha....

inheritance with Add
 子類別建立自己的操
作方式(mehotd)
 僅適用子類別
 Parent class呼叫會
出現錯誤
class Animal:
self.name = name
self.age = age
return voice
class Dog(Animal):
Animal.__init__(self, name,age) # 類別名稱後面不用加()、第一個參數須為self
self.color = color
def run(self):
return "Running fast"
doff = Animal("Doff",1)
print(poppy.run()) # Running fast
print(doff.run()) # AttributeError: 'Animal' object has no attribute 'run'

Python入門：5大概念初心者必備 2021/11/18

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