Pythonの辞書型(dictionary)の基本的な操作・ネストされた辞書・例題について

# 辞書の定義例
student = {
    "name": "ExE",
    "age": 20,
    "grade": "A"
}

# 値の取得
name = student["name"]  # "ExE" が取得される

# 値の更新
student["age"] = 21  # age の値が 21 に更新される

# 新しいキーと値の追加
student["major"] = "Physics"  # 新たに "major" キーが追加され、値は "Physics"

# キーと値の削除
del student["grade"]  # "grade" キーが辞書から削除される

# keys, values, items の例
keys = student.keys()  # dict_keys(['name', 'age', 'major'])
values = student.values()  # dict_values(['Alice', 21, 'Physics'])
items = student.items()  # dict_items([('name', 'Alice'), ('age', 21), ('major', 'Physics')])

# 辞書のすべてのキーと値をループで処理
for key, value in student.items():
    print(f"{key}: {value}")

# キーが存在しない場合にデフォルト値を返す
major = student.get("major", "Unknown")  # 存在すれば "Physics", 存在しなければ "Unknown" を返す

# ネストされた辞書の例
students = {
    "Alice": {"age": 20, "grade": "A"},
    "Bob": {"age": 22, "grade": "B"}
}

# ネストされた辞書へのアクセス
alice_age = students["Alice"]["age"]  # 20 が取得される

fruit_prices = {
    "apple": 100,
    "banana": 50,
    "orange": 70
}

{'apple': 100, 'banana': 60, 'orange': 70}

fruit_prices = {
    "apple": 100,
    "banana": 50,
    "orange": 70
}
fruit_prices["banana"] += 10
print(fruit_prices)

student_scores = {
    "MoM": 85,
    "EoE": 78,
    "ToE": 92
}

平均点: 85.0

student_scores = {
    "MoM": 85,
    "EoE": 78,
    "ToE": 92
}
average_score = sum(student_scores.values()) / len(student_scores)
print("平均点:", average_score)

city_population = {
    "Tokyo": 14000000,
    "Osaka": 8800000,
    "Nagoya": 2300000,
    "Fukuoka": 1500000,
    "Kyoto": 800000
}

{'Tokyo': 14000000, 'Osaka': 8800000, 'Nagoya': 2300000, 'Fukuoka': 1500000}

city_population = {
    "Tokyo": 14000000,
    "Osaka": 8800000,
    "Nagoya": 2300000,
    "Fukuoka": 1500000,
    "Kyoto": 800000
}
large_cities = {city: population for city, population in city_population.items() if population >= 1000000}
print(large_cities)

inventory = {
    "notebook": 120,
    "pencil": 85,
    "eraser": 40
}

{'notebook': 120, 'pencil': 85, 'eraser': 40, 'pen': 50

inventory = {
    "notebook": 120,
    "pencil": 85,
    "eraser": 40
}
inventory["pen"] = 50
print(inventory)

prices = {
    "apple": 100,
    "banana": 60,
    "cherry": 200
}

['apple', 'banana', 'cherry']

prices = {
    "apple": 100,
    "banana": 60,
    "cherry": 200
}
keys_list = list(prices.keys())
print(keys_list)