如何在对象列表中添加 2 个字典值

Question

我有这样的课程：

class item
{
    public int Id { get; set; }
    public Dictionary<string, int> Data { get; set; }
}

我有 2 个列表包含这样的类对象：

item obj1 = new item();
obj1.Id = 1;
obj1.Data = new Dictionary<string, int>();
obj1.Data.Add("1", 11);
obj1.Data.Add("2", 12);
obj1.Data.Add("3", 13);

item obj2 = new item();
obj2.Id = 2;
obj2.Data = new Dictionary<string, int>();
obj2.Data.Add("1", 21);
obj2.Data.Add("2", 22);
obj2.Data.Add("3", 23);

item obj3 = new item();
obj3.Id = 3;
obj3.Data = new Dictionary<string, int>();
obj3.Data.Add("1", 31);
obj3.Data.Add("2", 32);
obj3.Data.Add("3", 33);

item obj4 = new item();
obj4.Id = 1;
obj4.Data = new Dictionary<string, int>();
obj4.Data.Add("1", 41);
obj4.Data.Add("2", 42);
obj4.Data.Add("3", 43);

item obj5 = new item();
obj5.Id = 2;
obj5.Data = new Dictionary<string, int>();
obj5.Data.Add("1", 51);
obj5.Data.Add("2", 52);
obj5.Data.Add("3", 53);

item obj6 = new item();
obj6.Id = 3;
obj6.Data = new Dictionary<string, int>();
obj6.Data.Add("1", 61);
obj6.Data.Add("2", 62);
obj6.Data.Add("3", 63);

List<item> lst1 = new List<item>();
lst1.Add(obj1);
lst1.Add(obj2);
lst1.Add(obj3);

List<item> lst2 = new List<item>();
lst2.Add(obj4);
lst2.Add(obj5);
lst2.Add(obj6);

现在我想根据对象的 id 和字典键添加字典的值。结果将是这样的：

List<item> result = new List<item>();
result[0].Id = 1
result[0].Data["1"] = 52  // obj1.Data[1] + obj4.Data[1]
result[0].Data["2"] = 54  // obj1.Data[2] + obj4.Data[2]
result[0].Data["3"] = 56  // obj1.Data[3] + obj4.Data[3]

result[1].Id = 2
result[1].Data["1"] = 72  // obj2.Data[1] + obj5.Data[1]
result[1].Data["2"] = 74  // obj2.Data[2] + obj5.Data[2]
result[1].Data["3"] = 76  // obj2.Data[3] + obj5.Data[3]

result[2].Id = 3
result[2].Data["1"] = 92  // obj3.Data[1] + obj6.Data[1]
result[2].Data["2"] = 94  // obj3.Data[2] + obj6.Data[2]
result[2].Data["3"] = 96  // obj3.Data[3] + obj6.Data[3]

获得此结果的最佳方法是什么？

谢谢

Answer 1

首先，您作为示例显示的输出是错误的。例如，obj3.Data[1] + obj6.Data[1] 等于 92，而不是 56。

因此，LINQ 的所有优点都在这里：

var result = lst1.Join(lst2, x => x.Id, y => y.Id, (x, y) => new item
             {
                Id = x.Id,
                Data = x.Data.Join(y.Data, 
                                   a => a.Key,
                                   b => b.Key, 
                                   (a, b) => new { a.Key, Value = a.Value + b.Value }).ToDictionary(r => r.Key, t => t.Value)
             }).ToList();

如你所愿，结果是：

result[0].Id = 1
result[0].Data["1"] = 52  // obj1.Data[1] + obj4.Data[1]
result[0].Data["2"] = 54  // obj1.Data[2] + obj4.Data[2]
result[0].Data["3"] = 56  // obj1.Data[3] + obj4.Data[3]

result[1].Id = 2
result[1].Data["1"] = 72  // obj2.Data[1] + obj5.Data[1]
result[1].Data["2"] = 74  // obj2.Data[2] + obj5.Data[2]
result[1].Data["3"] = 76  // obj2.Data[3] + obj5.Data[3]

result[2].Id = 3
result[2].Data["1"] = 92  // obj3.Data[1] + obj6.Data[1]
result[2].Data["2"] = 94  // obj3.Data[2] + obj6.Data[2]
result[2].Data["3"] = 96  // obj3.Data[3] + obj6.Data[3]

Answer 2

这是一个更长的方法，但它确实允许您使用单个函数添加多个项目列表列表，并且可能更容易理解/调试，具体取决于您的 Linq 掌握程度：

private static List<Item> AddItemLists(List<List<Item>> itemLists)
{
    if (itemLists == null) throw new ArgumentNullException("itemLists");

    var result = new List<Item>();

    foreach (var itemList in itemLists)
    {
        foreach (var item in itemList)
        {
            var existingItemWithId = result.FirstOrDefault(i => i.Id == item.Id);

            if (existingItemWithId == null)
            {
                result.Add(item);
            }
            else
            {
                foreach (var itemData in item.Data)
                {
                    if (existingItemWithId.Data.ContainsKey(itemData.Key))
                    {
                        existingItemWithId.Data[itemData.Key] += itemData.Value;
                    }
                    else
                    {
                        existingItemWithId.Data.Add(itemData.Key, itemData.Value);
                    }
                }
            }
        }
    }

    return result;
}

示例用法：

var obj1 = new Item {Id = 1, Data = 
    new Dictionary<string, int> {{"1", 11}, {"2", 12}, {"3", 13}}};
var obj2 = new Item {Id = 2, Data = 
    new Dictionary<string, int> {{"1", 21}, {"2", 22}, {"3", 23}}};
var obj3 = new Item {Id = 3, Data = 
    new Dictionary<string, int> {{"1", 31}, {"2", 32}, {"3", 33}}};
var obj4 = new Item {Id = 1, Data = 
    new Dictionary<string, int> {{"1", 41}, {"2", 42}, {"3", 43}}};
var obj5 = new Item {Id = 2, Data = 
    new Dictionary<string, int> {{"1", 51}, {"2", 52}, {"3", 53}}};
var obj6 = new Item {Id = 3, Data = 
    new Dictionary<string, int> {{"1", 61}, {"2", 62}, {"3", 63}}};

// Three lists of items that we want to 'add'
var lst1 = new List<Item> {obj1, obj2};
var lst2 = new List<Item> {obj3, obj4};
var lst3 = new List<Item> {obj5, obj6};

// Add up as many lists of items that you want
var result = AddItemLists(new List<List<Item>> {lst1, lst2, lst3});

结果如下：