列表

Python for Developers 入门

Jasmin Ludolf

Senior Data Science Content Developer

问题

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

用列表解决！

列表：在一个变量中存储多个值
- 可包含任意数据类型组合

# 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]

检查数据类型

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

<class 'list'>

访问列表元素

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

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

列表是有序且有索引的
- Python 为第一个元素分配的索引从0开始

访问列表元素

列表=[]
访问元素=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

获取列表最后一个元素

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

访问多个元素

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]
末尾索引需加 1，因为：
- Python 返回到该索引为止，不包含该索引

访问多个元素

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']

按步长访问

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

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

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

返回索引为 0、2、4 的项

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

['tomatoes', 'olive oil']

返回索引为 1 和 4 的项

Passons à la pratique !

Python for Developers 入门