c#从子组中选择副本

Question

我想过滤掉"然后选择每个有重复id的唯一位置，无论名称如何:

数据设置

var list = new[]
{
new { id = 3, Name = "", Location = "LocationA" },
new { id = 2, Name = "", Location = "LocationA" },
new { id = 1, Name = "T", Location = "LocationB" },
new { id = 2, Name = "H", Location = "LocationB" },
new { id = 3, Name = "E", Location = "LocationB" },
new { id = 3, Name = "R", Location = "LocationB" },
new { id = 5, Name = "U", Location = "LocationC" },
new { id = 5, Name = "S", Location = "LocationC" },
new { id = 5, Name = "S", Location = "LocationD" },
new { id = 4, Name = "O", Location = "LocationD" },
new { id = 4, Name = "Z", Location = "LocationE" },
};

查询

var query1 = list
.Where(s => s.Name != "")
.GroupBy(g => g.Location)
.Where(w => w.Select(s => s.Location).Count() > 1)
.SelectMany(s => s)
.GroupBy(g => g.id)
.Where(w => w.Select(s => s.id).Count() > 1)
.SelectMany(s => s)
.ToList();
Console.WriteLine("outputn" + string.Join("n", query1));

{ id = 3, Name = E, Location = LocationB }
{ id = 3, Name = R, Location = LocationB }
{ id = 5, Name = U, Location = LocationC }
{ id = 5, Name = S, Location = LocationC }
{ id = 5, Name = S, Location = LocationD }

vs我真正想要的

{ id = 3, Name = E, Location = LocationB }
{ id = 3, Name = R, Location = LocationB }
{ id = 5, Name = U, Location = LocationC }
{ id = 5, Name = S, Location = LocationC }

LocationD has IDs 4 &所以它应该被过滤掉，但我做不到。我做错了什么?我该如何改正呢?

Answer 1

给定

var list = new[]
{
new { id = 3, Name = "", Location = "LocationA" },
new { id = 2, Name = "", Location = "LocationA" },
new { id = 1, Name = "T", Location = "LocationB" },
new { id = 2, Name = "H", Location = "LocationB" },
new { id = 3, Name = "E", Location = "LocationB" },
new { id = 3, Name = "R", Location = "LocationB" },
new { id = 5, Name = "U", Location = "LocationC" },
new { id = 5, Name = "S", Location = "LocationC" },
new { id = 5, Name = "S", Location = "LocationD" },
new { id = 4, Name = "O", Location = "LocationD" },
new { id = 4, Name = "Z", Location = "LocationE" },
};

var results = list
.Where(s => s.Name != "")
.GroupBy(x => new {x.id, x.Location})
.Where(g => g.Count() > 1)
.SelectMany(y => y);
foreach (var result in results)
Console.WriteLine($"{result.id}, {result.Name}, {result.Location}");

3, E, LocationB
3, R, LocationB
5, U, LocationC
5, S, LocationC

Answer 2

按id和Location分组。且.Count()大于1

var query1 = list
.Where(s => s.Name != "")
.GroupBy(g => new { g.Location, g.id })
.Where(g => g.Count() > 1)
.SelectMany(g => g)
.ToList();

样本演示