试试这个扩展方法。希望这能有所帮助。

public static class DistinctHelper
{
    public static IEnumerable<TSource> DistinctBy<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)
    {
        var identifiedKeys = new HashSet<TKey>();
        return source.Where(element => identifiedKeys.Add(keySelector(element)));
    }
}

用法:

var outputList = sourceList.DistinctBy(x => x.TargetProperty);

你有三个选项来删除列表中的重复项:

Use a a custom equality comparer and then use Distinct(new DistinctItemComparer()) as @Christian Hayter mentioned. Use GroupBy, but please note in GroupBy you should Group by all of the columns because if you just group by Id it doesn't remove duplicate items always. For example consider the following example: List<Item> a = new List<Item> { new Item {Id = 1, Name = "Item1", Code = "IT00001", Price = 100}, new Item {Id = 2, Name = "Item2", Code = "IT00002", Price = 200}, new Item {Id = 3, Name = "Item3", Code = "IT00003", Price = 150}, new Item {Id = 1, Name = "Item1", Code = "IT00001", Price = 100}, new Item {Id = 3, Name = "Item3", Code = "IT00003", Price = 150}, new Item {Id = 3, Name = "Item3", Code = "IT00004", Price = 250} }; var distinctItems = a.GroupBy(x => x.Id).Select(y => y.First()); The result for this grouping will be: {Id = 1, Name = "Item1", Code = "IT00001", Price = 100} {Id = 2, Name = "Item2", Code = "IT00002", Price = 200} {Id = 3, Name = "Item3", Code = "IT00003", Price = 150} Which is incorrect because it considers {Id = 3, Name = "Item3", Code = "IT00004", Price = 250} as duplicate. So the correct query would be: var distinctItems = a.GroupBy(c => new { c.Id , c.Name , c.Code , c.Price}) .Select(c => c.First()).ToList(); 3.Override Equal and GetHashCode in item class: public class Item { public int Id { get; set; } public string Name { get; set; } public string Code { get; set; } public int Price { get; set; } public override bool Equals(object obj) { if (!(obj is Item)) return false; Item p = (Item)obj; return (p.Id == Id && p.Name == Name && p.Code == Code && p.Price == Price); } public override int GetHashCode() { return String.Format("{0}|{1}|{2}|{3}", Id, Name, Code, Price).GetHashCode(); } } Then you can use it like this: var distinctItems = a.Distinct();

var distinctItems = items.GroupBy(x => x.Id).Select(y => y.First());

一个通用的扩展方法:

public static class EnumerableExtensions
{
    public static IEnumerable<T> DistinctBy<T, TKey>(this IEnumerable<T> enumerable, Func<T, TKey> keySelector)
    {
        return enumerable.GroupBy(keySelector).Select(grp => grp.First());
    }
}

用法示例:

var lstDst = lst.DistinctBy(item => item.Key);

另一种变通方法，不美观买不可行。

我有一个XML文件，其中有一个名为“MEMDES”的元素，具有“GRADE”和“SPD”两个属性，用于记录RAM模块信息。 SPD中有很多重复的项目。

下面是我用来删除重复项的代码:

        IEnumerable<XElement> MList =
            from RAMList in PREF.Descendants("MEMDES")
            where (string)RAMList.Attribute("GRADE") == "DDR4"
            select RAMList;

        List<string> sellist = new List<string>();

        foreach (var MEMList in MList)
        {
            sellist.Add((string)MEMList.Attribute("SPD").Value);
        }

        foreach (string slist in sellist.Distinct())
        {
            comboBox1.Items.Add(slist);
        }

这就是我如何能够通过Linq分组。希望能有所帮助。

var query = collection.GroupBy(x => x.title).Select(y => y.FirstOrDefault());