C#使用Linq实现简单去重处理

using system;
using system.collections.generic;
using system.linq;
 
public class program
{
    public static void main()
    {
        // 创建一些示例实体对象
        var people = new list<person>
        {
            new person { name = "alice", age = 30, city = "new york" },
            new person { name = "bob", age = 25, city = "los angeles" },
            new person { name = "alice", age = 30, city = "new york" },//重复的
            new person { name = "charlie", age = 35, city = "chicago" },
            new person { name = "alice", age = 28, city = "san francisco" }
        };
 
        // 1. 单字段去重
        var uniquenamefields = people.distinctby(p =>p.name).tolist();
        console.writeline("指定字段（name）去重结果,重复则保留第一条:");
        foreach (var person in uniquenamefields)
        {
            console.writeline($"name: {person.name}, age: {person.age}, city: {person.city}");
        }
 
        // 2. 多字段去重
        var uniquenameagefields = people.distinctby(p => new { p.name, p.age }).tolist();
        console.writeline("\n指定字段（name, age）去重结果,重复则保留第一条:");
        foreach (var person in uniquenameagefields)
        {
            console.writeline($"name: {person.name}, age: {person.age}, city: {person.city}");
        }
 
        //3.全字段去重
        // 通过 groupby 按 name 和 age 字段去重
        var uniquepeople = people.distinctby(p => new { p.name, p.age, p.city }).tolist();
        console.writeline("\n全字段去重:");
        foreach (var person in uniquepeople)
        {
            console.writeline($"name: {person.name}, age: {person.age}, city: {person.city}");
        }
    }
}
 
public class person
{
    public string name { get; set; }
    public int age { get; set; }
    public string city { get; set; }
}

people.distinct().tolist()

/// <summary>
/// 通用的全字段去重方法
/// </summary>
/// <returns></returns>
public static ienumerable<t> distinctbyallfields<t>(ienumerable<t> items)
{
    // 获取 t 类型的所有字段值
    var properties = typeof(t).getproperties(bindingflags.public | bindingflags.instance);
 
    return items
        .groupby(item => string.join(",", properties.select(p => p.getvalue(item))))  // 按所有字段值连接生成唯一标识符
        .select(group => group.first());  // 取每组的第一个元素
}

using system;
using system.collections.generic;
using system.linq;
using system.reflection;
 
public class program
{
    public static void main()
    {
        // 创建一些示例实体对象
        var people = new list<person>
        {
            new person { name = "alice", age = 30, city = "new york" },
            new person { name = "bob", age = 25, city = "los angeles" },
            new person { name = "alice", age = 30, city = "new york" },
            new person { name = "charlie", age = 35, city = "chicago" },
            new person { name = "alice", age = 28, city = "san francisco" }
        };
 
        // 调用封装的去重方法
        var uniquepeople = distinctbyallfields(people).tolist();
 
        console.writeline("根据所有字段去重的结果:");
        foreach (var person in uniquepeople)
        {
            console.writeline($"name: {person.name}, age: {person.age}, city: {person.city}");
        }
    }
 
    /// <summary>
    /// 通用的全字段去重方法
    /// </summary>
    /// <returns></returns>
    public static ienumerable<t> distinctbyallfields<t>(ienumerable<t> items)
    {
        // 获取 t 类型的所有字段值
        var properties = typeof(t).getproperties(bindingflags.public | bindingflags.instance);
 
        return items
            .groupby(item => string.join(",", properties.select(p => p.getvalue(item))))  // 按所有字段值连接生成唯一标识符
            .select(group => group.first());  // 取每组的第一个元素
    }
}
 
public class person
{
    public string name { get; set; }
    public int age { get; set; }
    public string city { get; set; }
}