检查对象列表中的重复项C#
检查对象列表中的重复项C#
提问于 2013-04-25 00:26:20
我正在寻找一种非常快速的方法来检查对象列表中的重复项。
我正在考虑简单地遍历列表并以这种方式进行手动比较，但我认为linq可能提供了一个更优雅的解决方案……
假设我有一个物体。
public class dupeCheckee
{
public string checkThis { get; set; }
public string checkThat { get; set; }
dupeCheckee(string val, string val2)
{
checkThis = val;
checkThat = val2;
}
}我有一个这些对象的列表
List<dupeCheckee> dupList = new List<dupeCheckee>();
dupList.Add(new dupeCheckee("test1", "value1"));
dupList.Add(new dupeCheckee("test2", "value1"));
dupList.Add(new dupeCheckee("test3", "value1"));
dupList.Add(new dupeCheckee("test1", "value1"));//dupe
dupList.Add(new dupeCheckee("test2", "value1"));//dupe...
dupList.Add(new dupeCheckee("test4", "value1"));
dupList.Add(new dupeCheckee("test5", "value1"));
dupList.Add(new dupeCheckee("test1", "value2"));//not dupe我要找出名单里的那些笨蛋。当我找到它时，我需要做一些额外的逻辑，而不是一定要删除它们。
当我使用linq时，我的GroupBy抛出了一个异常...
'System.Collections.Generic.List<dupeCheckee>' does not contain a definition for 'GroupBy' and no extension method 'GroupBy' accepting a first argument of type 'System.Collections.Generic.List<dupeCheckee>' could be found (are you missing a using directive or an assembly reference?)告诉我我错过了一个图书馆。不过，我很难弄清楚到底是哪一个。
一旦我弄清楚了这一点，我将如何本质上检查这两个条件...IE checkThis和checkThat都出现多次吗？
更新:我想出了什么
这是我在快速研究后想出的linq查询...
test.Count != test.Select(c => new { c.checkThat, c.checkThis }).Distinct().Count()我不确定这是否一定比这个答案更好。
var duplicates = test.GroupBy(x => new {x.checkThis, x.checkThat})
.Where(x => x.Skip(1).Any());我知道我可以将第一个语句放入if else子句中。我还运行了一个快速测试。当我期望0的时候，重复列表返回给我1，但它确实正确地调用了我使用的其中一个集合中有重复的事实。
另一种方法完全符合我的期望。以下是我用来测试这一点的数据集。
Dupes：
List<DupeCheckee> test = new List<DupeCheckee>{
new DupeCheckee("test0", "test1"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test1", "test2"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test2", "test3"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test3", "test3"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test0", "test5"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test1", "test6"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test2", "test7"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test3", "test8"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test0", "test5"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test1", "test1"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test2", "test2"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test3", "test3"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test4", "test4"),//{ checkThis = "test", checkThat = "test1"}
};没有上当受骗。
List<DupeCheckee> test2 = new List<DupeCheckee>{
new DupeCheckee("test0", "test1"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test1", "test2"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test2", "test3"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test3", "test3"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test4", "test5"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test5", "test6"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test6", "test7"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test7", "test8"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test8", "test5"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test9", "test1"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test2", "test2"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test3", "test3"),//{ checkThis = "test", checkThat = "test1"}
new DupeCheckee("test4", "test4"),//{ checkThis = "test", checkThat = "test1"}
};页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/16197290
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