Pythonのupdate関数で辞書を効率的に更新する方法と活用7選

my_dict = {'apple': 1, 'banana': 2}
my_dict['cherry'] = 3  # 新しいキーと値の追加
my_dict['apple'] = 5   # 既存のキーの値を変更

print(my_dict)

fruits = {'apple': 1, 'banana': 2}
fruits.update({'cherry': 3})

print(fruits)

fruits = {'apple': 1, 'banana': 2}
fruits.update({'apple': 5, 'orange': 4})

print(fruits)

inventory = {'apples': 10, 'bananas': 15}
new_items = {'cherries': 20, 'dates': 25, 'apples': 12}

inventory.update(new_items)
print(inventory)

stock = {'widget_a': 100, 'widget_b': 200}
stock.update(widget_c=300, widget_d=400)

print(stock)

dict1 = {'a': 1, 'b': 2}
dict2 = {'c': 3, 'd': 4}
dict3 = {'e': 5, 'f': 6}

dict1.update(dict2, **dict3)
print(dict1)

original_dict = {'apple': 1, 'banana': 2, 'cherry': 3}
update_dict = {'apple': 5, 'date': 4}

original_dict.update({k: v for k, v in update_dict.items() if k in original_dict})
print(original_dict)

nested_dict = {
    'fruits': {'apple': 1, 'banana': 2},
    'vegetables': {'carrot': 3, 'potato': 4}
}

update_dict = {
    'fruits': {'cherry': 5},
    'vegetables': {'tomato': 6}
}

for key, value in update_dict.items():
    if key in nested_dict:
        nested_dict[key].update(value)
    else:
        nested_dict[key] = value

print(nested_dict)

{
    'fruits': {'apple': 1, 'banana': 2, 'cherry': 5},
    'vegetables': {'carrot': 3, 'potato': 4, 'tomato': 6}
}

my_dict = {'a': 1, 'b': 2}
update_list = [('c', 3), ('d', 4)]
update_tuple = (('e', 5), ('f', 6))

my_dict.update(update_list)
my_dict.update(update_tuple)
print(my_dict)

user_preferences = {'theme': 'dark'}
default_settings = {'theme': 'light', 'font_size': 12, 'language': 'en'}

user_preferences = {**default_settings, **user_preferences}
print(user_preferences)

original_dict = {'a': 1, 'b': 2, 'c': 3}
update_dict = {'b': 20, 'c': 30, 'd': 40}

original_dict.update({k: v * 2 for k, v in update_dict.items() if k in original_dict})
print(original_dict)

def create_user(name, age, **additional_info):
    user = {'name': name, 'age': age}
    user.update(additional_info)
    return user

new_user = create_user('Alice', 30, occupation='Engineer', city='Tokyo')
print(new_user)

import time

def traditional_method(dict_size):
    my_dict = {}
    start_time = time.time()
    for i in range(dict_size):
        my_dict[f'key_{i}'] = i
    end_time = time.time()
    return end_time - start_time

def update_method(dict_size):
    my_dict = {}
    update_dict = {f'key_{i}': i for i in range(dict_size)}
    start_time = time.time()
    my_dict.update(update_dict)
    end_time = time.time()
    return end_time - start_time

dict_size = 1000000  # 100万個のキーと値のペア

traditional_time = traditional_method(dict_size)
update_time = update_method(dict_size)

print(f"従来の方法の処理時間: {traditional_time:.4f}秒")
print(f"update関数の処理時間: {update_time:.4f}秒")
print(f"速度向上率: {(traditional_time / update_time - 1) * 100:.2f}%")

従来の方法の処理時間: 0.2763秒
update関数の処理時間: 0.1052秒
速度向上率: 162.64%

import sys

def measure_memory(func, dict_size):
    before = sys.getsizeof({})
    result = func(dict_size)
    after = sys.getsizeof(result)
    return after - before

def traditional_method(dict_size):
    my_dict = {}
    for i in range(dict_size):
        my_dict[f'key_{i}'] = i
    return my_dict

def update_method(dict_size):
    my_dict = {}
    update_dict = {f'key_{i}': i for i in range(dict_size)}
    my_dict.update(update_dict)
    return my_dict

dict_size = 100000  # 10万個のキーと値のペア

traditional_memory = measure_memory(traditional_method, dict_size)
update_memory = measure_memory(update_method, dict_size)

print(f"従来の方法のメモリ使用量: {traditional_memory} バイト")
print(f"update関数のメモリ使用量: {update_memory} バイト")
print(f"メモリ削減率: {(traditional_memory - update_memory) / traditional_memory * 100:.2f}%")

従来の方法のメモリ使用量: 4194304 バイト
update関数のメモリ使用量: 4194304 バイト
メモリ削減率: 0.00%

original_dict = {'a': 1, 'b': 2, 'c': 3}
update_dict = {'b': 20, 'd': 4}

original_dict.update(update_dict)
print(original_dict)

dict1 = {'a': [1, 2, 3], 'b': {'x': 10}}
dict2 = {'a': [4, 5], 'b': {'y': 20}}

dict1.update(dict2)
print(dict1)

# dict1['a']を変更
dict1['a'].append(6)
print(dict1)
print(dict2)

{'a': [4, 5], 'b': {'y': 20}}
{'a': [4, 5, 6], 'b': {'y': 20}}
{'a': [4, 5], 'b': {'y': 20}}

import threading

shared_dict = {}

def update_dict(key, value):
    global shared_dict
    temp_dict = {key: value}
    shared_dict.update(temp_dict)

threads = []
for i in range(1000):
    t = threading.Thread(target=update_dict, args=(f'key_{i}', i))
    threads.append(t)
    t.start()

for t in threads:
    t.join()

print(f"辞書の長さ: {len(shared_dict)}")

import json

def load_config(file_path):
    with open(file_path, 'r') as f:
        return json.load(f)

def save_config(config, file_path):
    with open(file_path, 'w') as f:
        json.dump(config, f, indent=2)

def update_config(file_path, **kwargs):
    config = load_config(file_path)
    config.update(kwargs)
    save_config(config, file_path)

# 設定ファイルの初期内容
initial_config = {
    "theme": "light",
    "font_size": 12,
    "language": "en"
}

config_path = "config.json"
save_config(initial_config, config_path)

# ユーザーが設定を変更
update_config(config_path, theme="dark", font_size=14)

# 更新後の設定を表示
updated_config = load_config(config_path)
print(json.dumps(updated_config, indent=2))

{
  "theme": "dark",
  "font_size": 14,
  "language": "en"
}

import sqlite3

def build_query(table, conditions=None, order_by=None, limit=None):
    query = f"SELECT * FROM {table}"
    params = {}

    if conditions:
        where_clause = " AND ".join([f"{k} = :{k}" for k in conditions.keys()])
        query += f" WHERE {where_clause}"
        params.update(conditions)

    if order_by:
        query += f" ORDER BY {order_by}"

    if limit:
        query += f" LIMIT {limit}"

    return query, params

# データベース接続（例としてSQLiteを使用）
conn = sqlite3.connect(':memory:')
cursor = conn.cursor()

# サンプルテーブルの作成
cursor.execute('''CREATE TABLE users
                  (id INTEGER PRIMARY KEY, name TEXT, age INTEGER)''')
cursor.executemany('INSERT INTO users (name, age) VALUES (?, ?)',
                   [('Alice', 30), ('Bob', 25), ('Charlie', 35)])

# クエリの構築と実行
conditions = {'age': 30}
query, params = build_query('users', conditions=conditions, order_by='name', limit=5)
print("構築されたクエリ:", query)
print("パラメータ:", params)

cursor.execute(query, params)
result = cursor.fetchall()
print("クエリ結果:", result)

conn.close()

構築されたクエリ: SELECT * FROM users WHERE age = :age ORDER BY name LIMIT 5
パラメータ: {'age': 30}
クエリ結果: [(1, 'Alice', 30)]

import json

def merge_api_responses(*responses):
    merged_data = {}
    for response in responses:
        merged_data.update(json.loads(response))
    return merged_data

# APIからのレスポンスを模擬
api_response1 = '{"user_id": 123, "username": "john_doe"}'
api_response2 = '{"email": "john@example.com", "age": 30}'
api_response3 = '{"interests": ["Python", "Data Science"], "location": "Tokyo"}'

merged_data = merge_api_responses(api_response1, api_response2, api_response3)
print(json.dumps(merged_data, indent=2))

{
  "user_id": 123,
  "username": "john_doe",
  "email": "john@example.com",
  "age": 30,
  "interests": [
    "Python",
    "Data Science"
  ],
  "location": "Tokyo"
}

my_dict = None
my_dict.update({'key': 'value'})  # エラー発生

my_dict = my_dict or {}  # my_dictがNoneの場合、空の辞書を作成
my_dict.update({'key': 'value'})

my_dict = {}
my_dict.update(42)  # エラー発生

my_dict = {}
my_dict.update({'key': 42})  # 正しい使い方

my_dict = {'a': 1, 'b': 2}
value = my_dict['non_existent_key']  # エラー発生

my_dict = {'a': 1, 'b': 2}
value = my_dict.get('non_existent_key', 'default_value')  # エラーを回避

original_dict = {'a': 1, 'b': 2}
update_dict = {'b': 3, 'c': 4}

print("更新前:", original_dict)
original_dict.update(update_dict)
print("更新後:", original_dict)

original_dict = {'a': 1, 'b': 2}
update_dict = {'b': 3, 'c': 4}

original_dict.update(update_dict)
assert original_dict == {'a': 1, 'b': 3, 'c': 4}, "予期しない更新結果"

import logging

logging.basicConfig(level=logging.DEBUG)
logger = logging.getLogger(__name__)

def update_with_logging(original_dict, update_dict):
    logger.debug(f"更新前: {original_dict}")
    original_dict.update(update_dict)
    logger.debug(f"更新後: {original_dict}")

update_with_logging({'a': 1, 'b': 2}, {'b': 3, 'c': 4})

user_preferences = {'theme': 'dark'}

# テーマが設定されていない場合のみ、デフォルト値を設定
user_preferences.setdefault('theme', 'light')
print(user_preferences)  # 既存の値は変更されない

# 言語設定が存在しない場合、デフォルト値を設定
user_preferences.setdefault('language', 'en')
print(user_preferences)  # 新しいキーと値が追加される

{'theme': 'dark'}
{'theme': 'dark', 'language': 'en'}

from collections import ChainMap

defaults = {'theme': 'light', 'language': 'en', 'timezone': 'UTC'}
user_settings = {'theme': 'dark'}

settings = ChainMap(user_settings, defaults)
print(settings['theme'])    # user_settingsから取得
print(settings['language']) # defaultsから取得

# 新しい設定を追加
settings['font_size'] = 14
print(settings)

# 元の辞書は変更されない
print(user_settings)
print(defaults)

dark
en
ChainMap({'theme': 'dark', 'font_size': 14}, {'theme': 'light', 'language': 'en', 'timezone': 'UTC'})
{'theme': 'dark', 'font_size': 14}
{'theme': 'light', 'language': 'en', 'timezone': 'UTC'}

# Python 3.9以降で動作
base_config = {'debug': False, 'log_level': 'INFO'}
user_config = {'debug': True}

# 辞書のマージ
merged_config = base_config | user_config
print(merged_config)

# 複数の辞書のマージも可能
extra_config = {'log_file': 'app.log'}
final_config = base_config | user_config | extra_config
print(final_config)

{'debug': True, 'log_level': 'INFO'}
{'debug': True, 'log_level': 'INFO', 'log_file': 'app.log'}