具有键和不同值计数的组List<Object>

Question

我试图想出一个解决方案来分组给定的键和值列表。

我需要这样分组: Key > Distinct值> Count。

例如。

XFN99 2 3 <= [CODE] [DISTINCT_VALUE] [OCCURANCE IN LIST]

我有一个返回List<ObjectPart>的方法。这个对象有一个public string code和public int value。

我需要在一个键中得到每个不同值的计数。

示例输入：

XFN999 2
XFN999 2
XFN999 2
XFN999 4
XFN999 8
XFN999 8
XFN999 8
BPN655 1
BPN675 2
BPN655 1

期望产出：

XFN999 2 => 3x
XFN999 4 => 1x
XFN999 8 => 3x
BPN655 1 => 2x
BPN675 2 => 1x

我试图使用LINQ获得成功，但失败了，因为它将每个键的值相加。

var distValsPerKey = S.getAllDiffs()
                      .Result
                      .GroupBy(x => x.code)
                      .Select(x => new { C_ = x.Key, V_ = x.Distinct().Count() });

使用我的解决方案输出：

BPN373 => 30
BPN374 => 35
BPN377 => 47
BPN378 => 43
BPN387 => 67
BPN388 => 49
BPN653 => 10
BPN654 => 15
BPN699 => 40
BPN700 => 45
BPN711 => 68
BPN723 => 13
BPN724 => 11
BPN853 => 5
BPN854 => 6
BPN877 => 99
BPN878 => 94
BPN505 => 92
BPN507 => 570
BPN508 => 617

我的解决方案基本上是对键的值进行求和，但我需要对每个键的不同值进行求和/计数。

例子如下：

获取List<ObjectPart>的输入

public async Task<List<ObjectPart>> getAllDiffs()
{
    List<ObjectPart> TEMP = new List<ObjectPart>();

    await Task.Run(() =>
            {
                using (IngresConnection CONN = new IngresConnection())
                {
                    string QUERY = SELECT_REDACTED;

                    try
                    {
                        using (IngresCommand CMD = new IngresCommand())
                        {

                            CONN.ConnectionString = "host=; userID=; pwd=; database=;";
                            CMD.Connection = CONN;
                            CMD.CommandText = QUERY;
                            CONN.Open();

                            using (IngresDataReader READ = CMD.ExecuteReader())
                            {
                                while (READ.Read())
                                {
                                    ObjectPart OP = new ObjectPart();

                                    OP.wenr = READ.GetValue(0).ToString().Trim();
                                    OP.difference = Convert.ToInt32(READ.GetInt32(1));

                                    TEMP.Add(OP);
                                }
                                READ.Close();
                                CONN.Close();
                            }
                        }
                    }
                    catch (Exception E)
                    {
                        CONN.Close();
                        CONN.Dispose();
                    }
                }
            });

    List<ObjectPart> OPS_SORTED = TEMP.OrderBy(m => m.code).ToList();

    return OPS_SORTED;
}

LINQ输入以获得所需的输出：

 var distValsPerKey = S.getAllDiffs()
                       .Result
                       .GroupBy(x => x.code)
                       .Select(x => new { C_ = x.Key, V_ = x.Distinct().Count() });
        
foreach(var OP in distValsPerKey)
{
    Console.WriteLine($"{OP.C_} = > {OP.V_}");
}

Answer 1

你想按代码和价值分组，对吧？因此，在您的GroupBy中这样做：

var distValsPerKey = S.getAllDiffs().Result
    .GroupBy(x => new { x.code, x.value })
    .Select(x => new { C_ = x.Key, V_ = x.Distinct().Count() });

您的其余代码应该按原样工作，尽管如果输出GroupBy对象的键，它将不完全符合您所需的格式。我得到的结果如下：

{ code = XFN999, value = 2 } => 3
{ code = XFN999, value = 4 } => 1
{ code = XFN999, value = 8 } => 3
{ code = BPN655, value = 1 } => 2
{ code = BPN675, value = 2 } => 1

如果这不是您想要的，并且希望C_成为示例输出中的文本字符串，那么请更改选择：

var distValsPerKey = S.getAllDiffs().Result
    .GroupBy(x => new { x.code, x.value })
    .Select(x => new { C_ = $"{x.Key.code} {x.Key.value}", 
                       V_ = x.Distinct().Count() });

这就提供了输出：

XFN999 2 => 3
XFN999 4 => 1
XFN999 8 => 3
BPN655 1 => 2
BPN675 2 => 1

Answer 2

鉴于以下投入：

List<(string code, int value)> input = new()
{
    ("XFN999", 2),
    ("XFN999", 2),
    ("XFN999", 2),
    ("XFN999", 4),
    ("XFN999", 8),
    ("XFN999", 8),
    ("XFN999", 8),
    ("BPN655", 1),
    ("BPN675", 2),
    ("BPN655", 1),
};

您可以获得如下所需的输出数据：

List<(string code, int value, int occurrences)> output =
    input
        .GroupBy(x => new { x.code, x.value })
        .Select(x => (x.Key.code, x.Key.value, x.Count()))
        .ToList();

​

​

要以您所追求的方式显示这一点，请执行以下操作：

foreach (var o in output)
    Console.WriteLine($"{o.code} {o.value} => {o.occurrences}");

这给了我：

XFN999 2 => 3
XFN999 4 => 1
XFN999 8 => 3
BPN655 1 => 2
BPN675 2 => 1