Dictionaries

1.

# 在 dictionary 中創造新的 key

dict_name[new_key] = new_value

2.

# 改變其中一個 key 的 value

dict_name[key] = new_value

3.

# 刪除一個 key

del dict_name[key_name]

 

---

stock = {
    "banana": 6,
    "apple": 0,
    "orange": 32,
    "pear": 15
}

del stock['banana']
print(stock)

{‘apple’: 0, ‘orange’: 32, ‘pear’: 15}

 

stock['apple']=2
print(stock)

{‘apple’: 2, ‘orange’: 32, ‘pear’: 15}

 

stock['banaba']=6
print(stock)

{‘apple’: 2, ‘orange’: 32, ‘pear’: 15, ‘banaba’: 6}

 

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應用

學習重點

1. Using for loops with lists and dictionaries
2. Writing functions with loops, lists, and dictionaries
3. Updating data in response to changes in the environment (for instance, decreasing the number of bananas in stock by 1 when you sell one).

shopping_list = ["banana", "orange", "apple"]

stock = {
    "banana": 6,
    "apple": 0,
    "orange": 32,
    "pear": 15
}

prices = {
    "banana": 4,
    "apple": 2,
    "orange": 1.5,
    "pear": 3
}

def compute_bill(food):
  total = 0
  for item in food:
    if stock[item] > 0:
    total = total + prices[item]
    stock[item] = stock[item] - 1
  return total