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@onigiri_san(Oni Giri)

プログラミング習得ログ ジェネレーター式

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演習問題はこちら

def analyze_sales_data(sales_records):
    """
    売上データを分析する総合関数
    引数: [(商品名, 価格, 販売数), (商品名, 価格, 販売数), ...]
    戻り値: {
        "total_revenue": 総売上,
        "best_seller": (商品名, 販売数),
        "most_profitable": (商品名, 売上金額),
        "summary": (商品数, 総販売数, 平均単価)
    }
    """
    # ここにコードを書いてください
    pass

# 期待する動作
sales = [
    ("ノートPC", 80000, 5),
    ("マウス", 2000, 20),
    ("キーボード", 5000, 15),
    ("モニター", 30000, 8)
]

analysis = analyze_sales_data(sales)
print(f"総売上: {analysis['total_revenue']:,}円")
print(f"最多販売: {analysis['best_seller'][0]} ({analysis['best_seller'][1]}個)")
print(f"最高売上: {analysis['most_profitable'][0]} ({analysis['most_profitable'][1]:,}円)")
print(f"サマリー: 商品{analysis['summary'][0]}種類, 総販売{analysis['summary'][1]}個, 平均単価{analysis['summary'][2]:,.0f}円")

私の書いたコード(エラーがあり、要件も読み間違っている)

def analyze_sales_data(sales_records):
    """
    売上データを分析する総合関数
    引数: [(商品名, 価格, 販売数), (商品名, 価格, 販売数), ...]
    戻り値: {
        "total_revenue": 総売上,
        "best_seller": (商品名, 販売数),
        "most_profitable": (商品名, 売上金額),
        "summary": (商品数, 総販売数, 平均単価)
    }
    """
    total_revenue=0
    best_seller=()
    most_profitable=()
    summary=()

    for name,price,quantitysold in sales_records:
        total_revenue = total_revenue+price 
        best_seller =max(sales_records ,key=lambda x:x[2])
        most_profitable=max(sales_records,key=lambda x:x[1])
        summary=sum(len(sales_records),len(key=lambda x:x[2]),sum(key=lambda x:x[2])/len(sales_records))

    
    return {
            'total_revenue':total_revenue,
            'best_seller':best_seller,
            'most_profitable':most_profitable,
            'summary':summary
            }
# 期待する動作
sales = [
    ("ノートPC", 80000, 5),
    ("マウス", 2000, 20),
    ("キーボード", 5000, 15),
    ("モニター", 30000, 8)
]
analysis = analyze_sales_data(sales)
print(f"総売上: {analysis['total_revenue']:,}円")
print(f"最多販売: {analysis['best_seller'][0]} ({analysis['best_seller'][1]}個)")
print(f"最高売上: {analysis['most_profitable'][0]} ({analysis['most_profitable'][1]:,}円)")
print(f"サマリー: 商品{analysis['summary'][0]}種類, 総販売{analysis['summary'][1]}個, 平均単価{analysis['summary'][2]:,.0f}円")

正解版（1）

def analyze_sales_data(sales_records):
    """
    売上データを分析する総合関数
    """
    total_revenue = 0
    
    for name, price, quantity_sold in sales_records:
        total_revenue = total_revenue + (price * quantity_sold)  # 価格×数量
    
    # ループの外で計算
    best_seller = max(sales_records, key=lambda x: x[2])
    most_profitable = max(sales_records, key=lambda x: x[1] * x[2])  # 価格×数量で最高売上
    
    # summary の正しい計算
    item_count = len(sales_records)  # 商品数
    total_quantity = sum(x[2] for x in sales_records)  # 総販売数
    average_price = total_revenue / total_quantity  # 平均単価
    
    summary = (item_count, total_quantity, average_price)
    
    return {
        'total_revenue': total_revenue,
        'best_seller': (best_seller[0], best_seller[2]),  # (商品名, 販売数)
        'most_profitable': (most_profitable[0], most_profitable[1] * most_profitable[2]),  # (商品名, 売上金額)
        'summary': summary
    }

正解版（2）更に効率化

def analyze_sales_data(sales_records):
    """売上データを分析する総合関数"""
    total_revenue = 0
    max_quantity = 0
    max_revenue = 0
    best_seller_item = None
    most_profitable_item = None
    total_quantity = 0
    
    # 1回のループで全て計算
    for name, price, quantity_sold in sales_records:
        revenue = price * quantity_sold
        total_revenue += revenue
        total_quantity += quantity_sold
        
        # 最多販売をチェック
        if quantity_sold > max_quantity:
            max_quantity = quantity_sold
            best_seller_item = (name, quantity_sold)
        
        # 最高売上をチェック
        if revenue > max_revenue:
            max_revenue = revenue
            most_profitable_item = (name, revenue)
    
    # サマリー計算
    item_count = len(sales_records)
    average_price = total_revenue / total_quantity if total_quantity > 0 else 0
    summary = (item_count, total_quantity, average_price)
    
    return {
        'total_revenue': total_revenue,
        'best_seller': best_seller_item,
        'most_profitable': most_profitable_item,
        'summary': summary
    }

# テスト
sales = [
    ("ノートPC", 80000, 5),      # 売上: 400,000円
    ("マウス", 2000, 20),        # 売上: 40,000円 ← 最多販売
    ("キーボード", 5000, 15),    # 売上: 75,000円
    ("モニター", 30000, 8)       # 売上: 240,000円
]

analysis = analyze_sales_data(sales)
print(f"総売上: {analysis['total_revenue']:,}円")  # 755,000円
print(f"最多販売: {analysis['best_seller'][0]} ({analysis['best_seller'][1]}個)")  # マウス (20個)
print(f"最高売上: {analysis['most_profitable'][0]} ({analysis['most_profitable'][1]:,}円)")  # ノートPC (400,000円)
print(f"サマリー: 商品{analysis['summary'][0]}種類, 総販売{analysis['summary'][1]}個, 平均単価{analysis['summary'][2]:,.0f}円")

正解をみてから1日たって、自分で以下のように書いてみた。

   variation= len(sales_records)
    quantity= sum(x[2]for x in sales_records)
    average = total_revenue / quantity
    summary=(variation,quantity,average)

ジェネレーター式の基本構文

sum(x[2] for x in sales_records)
#   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
#   これがジェネレータ式

基本パターン

関数(式 for 変数 in リスト)

forを使った従来の書き方

# 従来の書き方よりもジェネレーター式を使ったほうが効率的
total_quantity = 0
for x in sales_records:
    total_quantity += x[2]

覚えるべきパターン

# 合計
total = sum(x[インデックス] for x in リスト)

# 最大・最小
maximum = max(x[インデックス] for x in リスト)
minimum = min(x[インデックス] for x in リスト)

# 条件付き
filtered_sum = sum(x[インデックス] for x in リスト if 条件)

# 計算結果
calculated_sum = sum(x[1] * x[2] for x in リスト)  # 価格×数量など

この演習問題で最終的に私自身で書いたコード

def analyze_sales_data(sales_records):
    """
    売上データを分析する総合関数
    引数: [(商品名, 価格, 販売数), (商品名, 価格, 販売数), ...]
    戻り値: {
        "total_revenue": 総売上,
        "best_seller": (商品名, 販売数),
        "most_profitable": (商品名, 売上金額),
        "summary": (商品数, 総販売数, 平均単価)
    }
    """
    total_revenue=0
    best_seller=()
    most_profitable=()
    summary=()

    for name,price,quantitysold in sales_records:
        total_revenue = total_revenue+(price*quantitysold) 

    best_seller =max(sales_records ,key=lambda x:x[2])
    most_profitable=max(sales_records,key=lambda x:x[1]*x[2])

    variation= len(sales_records)
    quantity= sum(x[2]for x in sales_records)
    average = total_revenue / quantity
    summary=(variation,quantity,average)

    return {
            'total_revenue':total_revenue,
            'best_seller':best_seller,
            'most_profitable':most_profitable,
            'summary':summary
            }
# 期待する動作
sales = [
    ("ノートPC", 80000, 5),
    ("マウス", 2000, 20),
    ("キーボード", 5000, 15),
    ("モニター", 30000, 8)
]
analysis = analyze_sales_data(sales)
print(f"総売上: {analysis['total_revenue']:,}円")
print(f"最多販売: {analysis['best_seller'][0]} ({analysis['best_seller'][1]}個)")
print(f"最高売上: {analysis['most_profitable'][0]} ({analysis['most_profitable'][1]:,}円)")
print(f"サマリー: 商品{analysis['summary'][0]}種類, 総販売{analysis['summary'][1]}個, 平均単価{analysis['summary'][2]:,.0f}円")
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