Advanced Materials of Python

1: def yell(text):
2:     return text.upper() + '!'
3: 
4: print(yell('hello'))
5: bark = yell # assign給其他變數
6: print(bark('woof'))

1: def yell(text):
2:     return text.upper() + '!'
3: 
4: bark = yell
5: 
6: funcs = [bark, str.lower, str.capitalize]
7: 
8: for func in funcs:
9:     print(func('hey there!'))

 1: def yell(text):
 2:     return text.upper() + '!'
 3: 
 4: bark = yell
 5: 
 6: def greet(func):
 7:     greeting = func('Hi, I am a Python Program')
 8:     print(greeting)
 9: 
10: greet(bark)

1: list = map(function, iterable object)

1: def yellp(text):
2:     return text.upper() + '!'
3: 
4: bark = yell
5: 
6: list1 = ['hello', 'hey', 'hi']
7: print(list(map(bark, list1)))

1: def speak(text):
2:     def whisper(t):
3:         return t.lower() + '...'
4:     return whisper(text)
5: 
6: print(speak('Hello, world'))

 1: def get_speak_func(volume):
 2:     def whisper(text):
 3:         return text.lower() + '...'
 4:     def yell(text):
 5:         return text.upper() + '!'
 6:     if volume > 0.5:
 7:         return yell
 8:     else:
 9:         return whisper
10: 
11: print(get_speak_func(0.3))
12: print(get_speak_func(0.7))

 1: def get_speak_func(text, volume):
 2:     def whisper():
 3:         return text.lower() + '...'
 4:     def yell():
 5:         return text.upper() + '!'
 6:     if volume > 0.5:
 7:         return yell
 8:     else:
 9:         return whisper
10: 
11: func = get_speak_func('Hello, world', 0.7)
12: print(func())

1: class Addr:
2:     def __init__(self, n):
3:         self.n = n
4:     def __call__(self, x):
5:         return self.n + x
6: 
7: plus_3 = Addr(3) #建立Addr物件，屬性n=3
8: print(plus_3(4))

 1: def uppercase(func):
 2:     def wrapper():
 3:         original_result = func()
 4:         modified_result = original_result.upper()
 5:         return modified_result
 6:     return wrapper
 7: 
 8: @uppercase #以uppercase修飾greet
 9: def greet():
10:     return 'Hello'
11: 
12: print(greet())

 1: def strong(func):
 2:     def wrapper():
 3:         return f'<strong> { func() } </strong>'
 4:     return wrapper
 5: 
 6: def emphasis(func):
 7:     def wrapper():
 8:         return f'<em> { func() } </em>'
 9:     return wrapper
10: 
11: @strong
12: @emphasis
13: def greet():
14:     return 'Hello!'
15: 
16: print(greet)
17: print(greet())

 1: def trace(func):
 2:     def wrapper(*args, **kwargs):
 3:         print(f'trace: callable function {func.__name__}, with arguments: {args}, {kwargs}')
 4:         original_results = func(*args, **kwargs)
 5:         print(f'trace: function {func.__name__} reutrn results: {original_results}!')
 6:         return original_results
 7:     return wrapper
 8: 
 9: @trace
10: def say(name, line):
11:     return f'{name}, {line}'
12: 
13: print(say('James', 'hi'))

 1: import time
 2: def eval_time(func):
 3:     def wrapper(*args, **kwargs):
 4:         start = time.perf_counter()
 5:         res = func(*args, **kwargs)
 6:         finish = time.perf_counter()
 7:         print(f'Finished in {round(finish-start, 2)} second(s)')
 8:         return res
 9:     return wrapper
10: 
11: @eval_time
12: def sigma(n):
13:     sum = 0
14:     for i in range(n):
15:         sum = sum + i
16:     return sum
17: 
18: print(sigma(100000000))

 1: xs = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
 2: ys = list(xs) # shallow copy
 3: print(xs == ys) # 二者內容相同
 4: print(xs is ys) # 但為不同物件
 5: 
 6: xs.append([10, 11, 12])
 7: print(xs)
 8: print(ys)
 9: 
10: # 但若是修改二者相同的部份，如
11: xs[1][0] = 'X'
12: print(xs)
13: print(ys)

 1: import copy
 2: xs = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
 3: zs = copy.deepcopy(xs)
 4: 
 5: print(xs == zs)
 6: print(xs is zs)
 7: 
 8: xs[1][0] = 'X'
 9: print(xs)
10: print(zs)

 1: import copy
 2: 
 3: class Point:
 4:     def __init__(self, x, y):
 5:         self.x = x
 6:         self.y = y
 7:     def __repr__(self):
 8:         return f'Point({self.x}, {self.y})'
 9: 
10: a = Point(23, 42)
11: b = Point(23, 42)
12: #b = copy.copy(a)
13: print(a)
14: print(b)
15: print(a == b)
16: print(a is b)

 1: class Drink:
 2:     def __init__(self, name, price, counts):
 3:         self.name = name
 4:         self.price = price
 5:         self.counts = counts
 6: 
 7:     def costs(self):
 8:         return self.drink_costs(self.price, self.counts)
 9: 
10:     @classmethod
11:     def blacktea(cls):
12:         return cls('紅茶', 1, 25)
13: 
14:     @classmethod
15:     def coffee(cls):
16:         return cls('熱美式', 1, 50)
17: 
18:     @staticmethod
19:     def drink_costs(price, counts):
20:         return price * counts
21: 
22: drink1 = Drink.blacktea()
23: drink2 = Drink.coffee()
24: drink3 = Drink('義式', 60, 3)
25: print(f'{drink1.name}')
26: print(f'{drink2.price}')
27: print(f'{drink3.name!r} * {drink3.counts} = {drink3.costs()}')

 1: class Dog:
 2:     num_dogs = 0 #Demo class variable的適用時機
 3:     num_leg = 4
 4: 
 5:     def __init__(self, name):
 6:         self.name = name
 7:         self.__class__.num_dogs += 1
 8: 
 9: dd = Dog('DaiDai')
10: bd = Dog('Bad luck')
11: lk = Dog('Lucky')
12: bd.num_leg = 3
13: print(dd.num_leg)
14: print(bd.num_leg)
15: print(f'目前共有{Dog.num_dogs}隻狗')

 1: import collections
 2: 
 3: dict1 = {'one':1, 'two': 2}
 4: dict2 = {'two':'貳', 'three': 'III', 'four': 4}
 5: chain = collections.ChainMap(dict1, dict2)
 6: 
 7: print(chain)
 8: print(chain['two'])
 9: chain['five'] = 5
10: print(chain)

1: car1 = ['red', 3812, True] #list, 可變
2: car2 = ('blue', 3123, False) #tuple, 不可變
3: car3 = (343, 'black', True, 'James') #順序錯誤、欄位也不一致

1: Car = {
2:     'color': 'red',
3:     'mileage': 3213,
4:     'automatic': True
5: }
6: print(Car)
7: print(Car['color'])
8: Car['windshield'] = 'broken'
9: print(Car)

1: class Car:
2:     def __init__(self, color, mileage):
3:         self.color = color
4:         self.mileage = mileage
5: 
6: car = Car('red', 1234)
7: car.mileage = 4343 #可修改欄位內容
8: car.automatic = True #可新增欄位

 1: from typing import NamedTuple
 2: 
 3: class Car(NamedTuple):
 4:     color: str
 5:     mileage: float
 6:     automatic: bool
 7: 
 8: car = Car('red', 3123, True)
 9: print(car)
10: #car.mileage = 3123 # 不能變更欄位內容
11: #car.windshield = 'broken' #不能新增欄位
12: car2 = Car('blue', 'test', 1234)
13: print(car2)

1: from types import SimpleNamespace
2: 
3: car = SimpleNamespace(color = 'red',
4:                       mileage = 1341,
5:                       automatic = True)
6: 
7: car.color = 'blue'
8: print(car)

 1: from dataclasses import dataclass
 2: 
 3: @dataclass
 4: class Car:
 5:     color: str
 6:     mileage: float
 7:     automatic: bool
 8: 
 9:     def mileage_km(self): #可自訂method
10:         return self.mileage * 1.609
11: 
12: car = Car('red', 3123, True)
13: print(dir(car))
14: print(car.mileage_km)
15: print(car.__repr__)
16: 
17: @dataclass
18: class ElectronicCar(Car): #繼承
19:     charge: float = 0.0
20: 
21: car2 = ElectronicCar('white', 3123, True, 1000)
22: print(car2)
23: 

1: from struct import Struct
2: 
3: MyStruct = struct('1?f') #指定資料格式
4: data = MyStruct.pack(23, False, 42.0) #資料打包成二進位資料
5: print(data)
6: x = MyStruct.unpack(data)
7: print(x)

1: vowels = frozenset({'a', 'e', 'i', 'o', 'u'})
2: d = {vowels: 'hello'} # set變為dict的key
3: print(d)
4: 

 1: from collections import Counter
 2: 
 3: inventory = Counter()
 4: loot = {'sward': 1, 'bread': 3}  #裝備品名及數量
 5: inventory.update(loot)
 6: print(inventory)
 7: 
 8: more_loot = ['sward', 'coins']
 9: inventory.update(more_loot)
10: 
11: yet_more_loot = ['sward', 'bread', 'drink']
12: inventory.update(yet_more_loot)
13: print(inventory)

 1: a = []
 2: a.append('eating')
 3: a.append('sleeping')
 4: a.append('coding')
 5: print(a)
 6: a.pop()
 7: print(a)
 8: 
 9: #自head做push, pop
10: a.insert(0, 'drinking')
11: a.insert(0, 'playing')
12: a.pop(0)
13: print(a)

 1: from collections import deque
 2: 
 3: a = deque()
 4: 
 5: a.append('eating')
 6: a.append('sleeping')
 7: a.append('coding')
 8: print(a)
 9: a.pop()
10: print(a)
11: 
12: #自中間取值，效能差
13: print(a[1])
14: 

1: from queue import LifoQueue
2: s = LifoQueue()
3: s.put('eating')
4: s.put('sleeping')
5: s.put('coding')
6: print(s.get())
7: print(s.get())

 1: from collections import deque
 2: q = deque()
 3: q.append('eating')
 4: q.append('sleeping')
 5: q.append('coding')
 6: q.append('writing')
 7: print(q)
 8: print(q.popleft())
 9: print(q.popleft())
10: print(q)
11: 

1: import heapq
2: 
3: q = []
4: heapq.heappush(q, (2, 'coding'))
5: heapq.heappush(q, (1, 'eating'))
6: heapq.heappush(q, (3, 'sleeping'))
7: while q:
8:     next_item = heapq.heappop(q)
9:     print(next_item)

1: a = [1, 2, 3]
2: b = [4, 5, 6]
3: c = [7, 8, 9]
4: matrix = [a, b, c]
5: print(matrix)
6: print(list(zip(*matrix)))
7: print(list(zip(*reversed(matrix))))

1: list = [運算式 for 變數 in iterable object]

1: squares = [x ** 2 for x in range(10)]
2: print(squares)

1: list = [x ** 2 for x in range(10) if x % 2 == 0]
2: print(list)

1: setA = [x ** 2 for x in range(10)]
2: print(setA)
3: dicA = {x: x ** 2 for x in range(10)}
4: print(dicA)

1: list[index start: index end: step]

1: nums = [1, 2, 3, 4, 5, 6, 7, 8]
2: print(nums[::])
3: print(nums[1:6:2])
4: nums[1:6:2] = [10, 20, 30]
5: print(nums)
6: 

1: l = list(range(6))
2: print(l)
3: cl = l # 指向同一list
4: dl = l[::] # shallow copy
5: l[3] = 10
6: print(cl)
7: print(dl)