字典

Python for Developers 入门

Jasmin Ludolf

Senior Data Science Content Developer

配料清单

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


# 配料用量（克）
quantities = [500, 400, 15, 20, 30, 5]

字典

字典 = 键-值对

标注了单词（键）和定义（值）的词典

¹ https://unsplash.com/@sandym10

为何使用字典？

username
email
preferences

ip_address
location

配方缩放器：将配料与用量关联

用户信息

计算机网络

¹ User image by Bilobaba Vladimir, Aviavlad; https://unsplash.com/@jjying

创建字典

# 创建字典
recipe =

创建字典

# 创建字典
recipe = {

创建字典

# 创建字典
recipe = {"pasta"

创建字典

# 创建字典
recipe = {"pasta":

创建字典

# 创建字典
recipe = {"pasta": 500

创建字典

# 创建字典
recipe = {"pasta": 500,

创建字典

# 创建字典
recipe = {"pasta": 500,
          "tomatoes": 400,

创建字典

# 创建字典
recipe = {"pasta": 500,
          "tomatoes": 400, 
          "garlic": 15,
          "basil": 20, 
          "olive oil": 30,
          "salt": 5

创建字典

# 创建字典
recipe = {"pasta": 500,
          "tomatoes": 400, 
          "garlic": 15,
          "basil": 20, 
          "olive oil": 30,
          "salt": 5}

按键访问值

字典是有序的
- 允许通过键索引访问值
需要多少意面？

# 查找配料用量
print(recipe["pasta"])

获取所有值

# 获取字典的所有值
print(recipe.values())

dict_values([500, 400, 15, 20, 30, 5])

获取所有键

# 获取字典的所有键
print(recipe.keys())

dict_keys(['pasta', 'tomatoes', 'garlic', 'basil', 'olive oil', 'salt'])

查看整个字典

# 打印字典
print(recipe)

{'pasta': 500, 'tomatoes': 400, 'garlic': 15, 'basil': 20, 'olive oil': 30,
'salt': 5}

# 获取所有项（键-值对）
print(recipe.items())

dict_items([('pasta', 500), ('tomatoes', 400), ('garlic', 15), ('basil', 20), 
('olive oil', 30), ('salt', 5)])

添加键-值对

# 添加新的键-值对
recipe["parmesan"] = 50

print(recipe)

{'pasta': 500, 'tomatoes': 400, 'garlic': 15, 'basil': 20, 'olive oil': 30,
'salt': 5, 'parmesan': 50}

更新值

print(recipe)

{'pasta': 500, 'tomatoes': 400, 'garlic': 15, 'basil': 20, 'olive oil': 30,
'salt': 5, 'parmesan': 50}

# 更新已有键对应的值
recipe["pasta"] = 1000

print(recipe)

{'pasta': 1000, 'tomatoes': 400, 'garlic': 15, 'basil': 20, 'olive oil': 30,
'salt': 5, 'parmesan': 50}

重复键

# 创建含重复键的字典
recipe = {"pasta": 500, "garlic": 5, 
          "garlic": 15, "basil": 20, 
          "olive oil": 30, "salt": 5}


# 打印重复键的值
print(recipe["garlic"])

Passons à la pratique !

Python for Developers 入门