在Python中向字典中的特定键添加值

my_dict = {"key1": "value1", "key2": "value2"}
my_dict["key3"] = "value3"  # 向字典中添加新键值对
my_dict["key1"] = "new value"  # 更新已存在的键对应的值

my_dict = {"key1": "value1", "key2": "value2"}
new_dict = {"key3": "value3", "key1": "new value"}
my_dict.update(new_dict)  # 合并新字典到原字典

my_dict = {"key1": "value1", "key2": "value2"}
my_dict.setdefault("key3", "value3")  # 向字典中添加新键值对
my_dict.setdefault("key1", "new value")  # 不会更新已存在的键对应的值