Lists

Python 入門（開發者向）

Jasmin Ludolf

Senior Data Science Content Developer

問題

# Variables of ingredient names
ingredient_one = "pasta"
ingredient_two = "tomatoes"
ingredient_three = "garlic"
ingredient_four = "basil"
ingredient_five = "olive oil"
ingredient_six = "salt"

用清單來解救！

List：在單一變數中存多個值
- 可包含任意資料型別的組合

# List of ingredients
ingredients = ["pasta", "tomatoes", "garlic", "basil", "olive oil", "salt"]

# List of ingredients using variables as values
ingredients = [ingredient_one, ingredient_two, ingredient_three,
               ingredient_four, ingredient_five, ingredient_six]

檢查資料型別

# Check the data type of a list
print(type(ingredients))

<class 'list'>

存取清單元素

# Print all values in the list variable
print(ingredients)

['pasta', 'tomatoes', 'garlic', 'basil', 'olive oil', 'salt']

List 具順序與索引
- Python 從零開始給第一個元素編號

存取清單元素

List = []
存取元素 = a_list[index]

ingredients = ["pasta", "tomatoes",
"garlic", "basil", "olive oil", "salt"]

# Get the value at the first index
print(ingredients[0])

pasta

# Get the fourth element
print(ingredients[3])

basil

取得最後一個元素

ingredients = ["pasta", "tomatoes", "garlic", "basil", "olive oil", "salt"]

# Get the last element of a list
print(ingredients[5])

salt

# Get the last element of a list
print(ingredients[-1])

salt

存取多個元素

ingredients = ["pasta", "tomatoes", "garlic", "basil", "olive oil", "salt"]

# Access the second and third elements
print(ingredients[1:3])

["tomatoes", "garlic"]

[first_element:last_element + 1]
尾端索引要加 1，因為：
- Python 回傳到該索引「之前」但不包含它

存取多個元素

ingredients = ["pasta", "tomatoes", "garlic", "basil", "olive oil", "salt"]

# Access all elements from the third index onwards
print(ingredients[3:])

['basil', 'olive oil', 'salt']

# Get the first three elements
print(ingredients[:3])

['pasta', 'tomatoes', 'garlic']

交替存取

ingredients = ["pasta", "tomatoes", "garlic", "basil", "olive oil", "salt"]

# Access every second element
print(ingredients[::2])

['pasta', 'garlic', 'olive oil']]

回傳索引 0、2、4 的項目

# Access every third element, starting at the second
print(ingredients[1::3])

['tomatoes', 'olive oil']

回傳索引 1 與 4 的項目

一起來練習吧！

Python 入門（開發者向）