集合与元组

Python for Developers 入门

Jasmin Ludolf

Senior Data Science Content Developer

集合

包含唯一数据
不可变
- 可添加或删除元素，但不能修改其值
适合识别并去重
查找快（相比列表等结构）

创建集合

集合 = {}
: = 字典
无 : = 集合

# Create a set of ingredients
ingredients = {"pasta", "tomatoes", "pasta", 
                 "basil", "garlic", "olive oil", "salt"}
print(ingredients)

{'pasta', 'tomatoes', 'garlic', 'basil', 'olive oil', 'salt'}

转换为集合

# Existing list variable
ingredients_list = ["pasta", "tomatoes", "garlic", "basil"
                    "olive oil", "pasta", "salt"]


# Convert to a set
unique_ingredients = set(ingredients_list)


# Check the data type
type(unique_ingredients)

set

转换为集合

print(unique_ingredients)

{'pasta', 'tomatoes', 'garlic', 'basil', 'olive oil'}

集合的限制

无索引
- 不允许重复
- 不能用 [] 切片

# Trying to subset a set
print(unique_ingredients[0])

TypeError: 'set' object is not subscriptable

集合排序

ingredients = {"pasta", "tomatoes", "garlic", 
                 "basil", "olive oil", "salt"}


# Sorting a set
print(sorted(ingredients))

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

sorted() 返回列表

元组

不可变——创建后不可更改
- 不能添加值
- 不能删除值
- 不能修改值

有序
- 可用索引取值，如 [0]

适用于位置信息或标识符

笔记本电脑上的挂锁

¹ https://unsplash.com/@towfiqu999999

创建元组

# Creating a tuple
serving_sizes = (1, 2, 4, 6, 8)


# Convert another data structure to a tuple
ingredients_tuple = tuple(ingredients_list)

访问元组

# A tuple
serving_sizes = (1, 2, 4, 6, 8)

# Access the second element
print(serving_size[1])

Passons à la pratique !

Python for Developers 入门