コンテナ比較と包括的な内包表記

# 同じシナリオを異なるコンテナで実装

# シナリオ：学生名の保存
# リスト — 順序付けられ、追加／削除が容易
students_list = ["Alice", "Bob", "Charlie"]
students_list.append("Diana")
print(f"List: {students_list[0]}")    # Alice

# タプル — 固定（クラス名簿など）
students_tuple = ("Alice", "Bob", "Charlie")
# students_tuple[0] = "xxx"     # エラー！タプルはイミュータブル
print(f"Tuple: {students_tuple[0]}")   # Alice

# 辞書 — ID による高速検索
students_dict = {
    "001": "Alice",
    "002": "Bob",
    "003": "Charlie",
}
print(f"Dict: {students_dict['002']}")  # Bob — O(1) の速度

# セット — 重複除去（出席リストなど）
attendance = {"Alice", "Bob", "Charlie", "Alice"}
print(f"Set: {attendance}")            # {'Bob', 'Charlie', 'Alice'} — Alice は重複除去

numbers = range(1, 31)

# 3 で割り切れ、かつ 5 で割り切れる
filtered = [n for n in numbers if n % 3 == 0 and n % 5 == 0]
print(filtered)             # [15, 30]

# 3 で割り切れる、または 5 で割り切れる
filtered = [n for n in numbers if n % 3 == 0 or n % 5 == 0]
print(filtered)             # [3, 5, 6, 9, 10, 12, 15, 18, 20, 21, 24, 25, 27, 30]

# 座標ペアを生成 — 二重 for ループに相当
pairs = [(x, y) for x in range(3) for y in range(3)]
print(pairs)
# [(0, 0), (0, 1), (0, 2), (1, 0), (1, 1), (1, 2), (2, 0), (2, 1), (2, 2)]

# 条件付きネスト — 和が偶数のペアを見つける
pairs = [(x, y) for x in range(3) for y in range(3) if (x + y) % 2 == 0]
print(pairs)
# [(0, 0), (0, 2), (1, 1), (2, 0), (2, 2)]

# 内包表記での if-else — 位置が異なることに注意
numbers = [1, 2, 3, 4, 5, 6]

# if のみ（フィルタリング）— 後ろに配置
evens = [n for n in numbers if n % 2 == 0]

# if-else（変換）— 前に配置
result = ["even" if n % 2 == 0 else "odd" for n in numbers]
print(result)   # ['odd', 'even', 'odd', 'even', 'odd', 'even']

# 1 行で：フィルタ → 変換 → フォーマット
raw = ["  apple  ", "BANANA", "", "  CHERRY", None, "  date  "]

# None と空文字列を除外 → 空白を除去 → 先頭大文字
cleaned = [item.strip().capitalize() for item in raw if item and item.strip()]
print(cleaned)              # ['Apple', 'Banana', 'Cherry', 'Date']

['Apple', 'Banana', 'Cherry', 'Date']

# 基本的な辞書内包表記
squares = {x: x ** 2 for x in range(5)}
print(squares)              # {0: 0, 1: 1, 2: 4, 3: 9, 4: 16}

# 条件付き
even_squares = {x: x ** 2 for x in range(10) if x % 2 == 0}
print(even_squares)         # {0: 0, 2: 4, 4: 16, 6: 36, 8: 64}

# キーと値の反転
original = {"a": 1, "b": 2, "c": 3}
reversed_dict = {value: key for key, value in original.items()}
print(reversed_dict)        # {1: 'a', 2: 'b', 3: 'c'}

# 2 つのリストを辞書にマージ
names = ["Alice", "Bob", "Charlie"]
scores = [85, 92, 78]
result = {names[i]: scores[i] for i in range(len(names))}
print(result)               # {'Alice': 85, 'Bob': 92, 'Charlie': 78}

# zip() を使うとよりエレガント
result = {name: score for name, score in zip(names, scores)}
print(result)               # {'Alice': 85, 'Bob': 92, 'Charlie': 78}

# セット内包表記 — 自動重複除去
numbers = [1, 2, 2, 3, 3, 3, 4, 5, 5]
unique_squares = {x ** 2 for x in numbers}
print(unique_squares)       # {1, 4, 9, 16, 25}

# 条件付き
even_set = {x for x in range(20) if x % 2 == 0}
print(even_set)             # {0, 2, 4, 6, 8, 10, 12, 14, 16, 18}

# 記事の語彙を分析
article = """
Python is great. Python is powerful!
I love Python. JavaScript is also great.
But Python is my favorite.
"""

# すべての単語を抽出
words = article.lower().split()

# セット内包表記で重複除去
unique_words = {word.strip(".!,") for word in words}
print(f"Total words: {len(words)}")
print(f"Unique words: {len(unique_words)}")
print(f"All unique words: {sorted(unique_words)}")

Total words: 18
Unique words: 10
All unique words: ['also', 'but', 'favorite', 'great', 'is', 'javascript', 'love', 'my', 'python', 'i']