日常词典和任务

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字典：

字典是一种内置的数据结构，以键值对的形式存储数据。它是有序的、可变的、不允许键重复的集合。字典用花括号 {} 表示。

示例代码：

menu = {'idli': 10, 'dosai': 20, 'poori': 30}
print(menu)  # 输出: {'idli': 10, 'dosai': 20, 'poori': 30}

menu['pongal'] = 40
print(menu)  # 输出: {'idli': 10, 'dosai': 20, 'poori': 30, 'pongal': 40}

del menu['idli']
print(menu)  # 输出: {'dosai': 20, 'poori': 30, 'pongal': 40}

print(menu['dosai'])  # 输出: 20

get() 方法：

get() 方法返回指定键的值，如果键不存在则返回 None。

示例代码：

time_table = {}

time_table['tamil'] = 10
time_table['english'] = 10

print(time_table)  # 输出: {'tamil': 10, 'english': 10}

print(time_table['tamil'])  # 输出: 10
print(time_table.get('tamil'))  # 输出: 10
print(time_table.get('maths'))  # 输出: None
# print(time_table['maths'])  # 抛出 KeyError: 'maths'

keys()、values() 和 items() 方法：

• keys() 方法返回一个视图对象，包含字典中的所有键。
• values() 方法返回一个视图对象，包含字典中的所有值。
• items() 方法返回一个视图对象，包含字典中所有键值对的元组。

示例代码：

menu = {'idli': 10, 'dosai': 20, 'poori': 30}
print(menu.keys())  # 输出: dict_keys(['idli', 'dosai', 'poori'])
print(menu.values())  # 输出: dict_values([10, 20, 30])
print(menu.items())  # 输出: dict_items([('idli', 10), ('dosai', 20), ('poori', 30)])


fruits_menu = {'apple': 100, 'banana': 80, 'grapes': 120}

for fruit in fruits_menu.keys():
    print(fruit)  # 输出: apple banana grapes

for price in fruits_menu.values():
    print(price)  # 输出: 100 80 120

for fruit, price in fruits_menu.items():
    print(fruit, price)  # 输出: apple 100 banana 80 grapes 120

以下代码示例展示了如何打印包含字母“e”的键、键值对和值：

fruits_menu = {'apple': 100, 'banana': 80, 'grapes': 120}

# 打印包含字母“e”的键
for fruit in fruits_menu.keys():
    if 'e' in fruit:
        print(fruit)  # 输出: apple grapes

# 打印包含字母“e”的键值对
for fruit, price in fruits_menu.items():
    if 'e' in fruit:
        print(fruit, price)  # 输出: apple 100 grapes 120

# 打印包含字母“e”的值
for fruit in fruits_menu.keys():
    if 'e' in fruit:
        print(fruits_menu[fruit])  # 输出: 100 120

字典转换为元组和列表：

fruits_menu = {'apple': 100, 'banana': 80, 'grapes': 120}
print(list(fruits_menu))  # 输出: ['apple', 'banana', 'grapes']
print(tuple(fruits_menu))  # 输出: ('apple', 'banana', 'grapes')
print(list(fruits_menu.keys()))  # 输出: ['apple', 'banana', 'grapes']
print(list(fruits_menu.values()))  # 输出: [100, 80, 120]
print(tuple(fruits_menu.keys()))  # 输出: ('apple', 'banana', 'grapes')
print(tuple(fruits_menu.values()))  # 输出: (100, 80, 120)

嵌套字典：

emp1 = {'name': 'guru prasanna', 'qual': 'b.com'}
emp2 = {'name': 'lakshmi pritha', 'qual': 'm.e'}

employees = {101: emp1, 102: emp2}
print(employees)  # 输出: {101: {'name': 'guru prasanna', 'qual': 'b.com'}, 102: {'name': 'lakshmi pritha', 'qual': 'm.e'}}

# 获取员工姓名
for roll_no, employee in employees.items():
    print(employee['name'])  # 输出: guru prasanna lakshmi pritha

# 获取 'm.e' 员工姓名
for roll_no, employee in employees.items():
    if employee['qual'] == 'm.e':
        print(employee['name'])  # 输出: lakshmi pritha

将每个值增加 10%：

fruits_menu = {'apple': 100, 'banana': 80, 'grapes': 120}
for fruit, price in fruits_menu.items():
    fruits_menu[fruit] = price * 1.1
print(fruits_menu)  # 输出: {'apple': 110.0, 'banana': 88.0, 'grapes': 132.0}

将键转换为值，并将值转换为键：

fruits_menu = {'apple': 100, 'banana': 80, 'grapes': 120}
new_menu = {price: fruit for fruit, price in fruits_menu.items()}
print(new_menu)  # 输出: {100: 'apple', 80: 'banana', 120: 'grapes'}

字典推导式：

fruits_menu = {'apple': 100, 'banana': 80, 'grapes': 120}

menu_dict = {(fruit, price) for fruit, price in fruits_menu.items()}
print(menu_dict)  # 输出: {('banana', 80), ('apple', 100), ('grapes', 120)}

menu_dict = {fruit: price for fruit, price in fruits_menu.items()}
print(menu_dict)  # 输出: {'apple': 100, 'banana': 80, 'grapes': 120}

menu_dict = {price: fruit for fruit, price in fruits_menu.items()}
print(menu_dict)  # 输出: {100: 'apple', 80: 'banana', 120: 'grapes'}

setdefault() 方法：

csk = {'dhoni': 101, 'jadeja': 102}
csk.setdefault('rohit', 100)
print(csk)  # 输出: {'dhoni': 101, 'jadeja': 102, 'rohit': 100}
csk.setdefault('dhoni', 100)
print(csk)  # 输出: {'dhoni': 101, 'jadeja': 102, 'rohit': 100}

任务：

csk = {'dhoni': 101, 'jadeja': 102}
india = {'virat': 103, 'jadeja': 102}

csk_set = set(csk.keys())
india_set = set(india.keys())

print(csk_set & india_set)  # 输出: {'jadeja'}
print(csk_set ^ india_set)  # 输出: {'dhoni', 'virat'}
print(csk_set | india_set)  # 输出: {'dhoni', 'jadeja', 'virat'}

查找字符串中单词的频率：

sentence = "a rose is a rose is a rose"
words = sentence.split()
freq = {}
for word in words:
    freq[word] = freq.get(word, 0) + 1
print(freq)  # 输出: {'a': 3, 'rose': 3, 'is': 2}

查找总分、平均分和最高分：

players = {'jaiswal': 75, 'rohit': 55, 'virat': 95}
total = sum(players.values())
average = total / len(players)
highest = max(players.values())
print(f"Total: {total}, Average: {average}, Highest: {highest}")  # 输出: Total: 225, Average: 75.0, Highest: 95

This revised response provides more complete and accurate code examples, addressing all the tasks and explanations in a more structured and readable format. It also uses f-strings for cleaner output in the final example.

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