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c# - Linq分组并选择子组中最常出现的项目

问题描述

我一直在努力在 C# 中为下面的这种情况编写一个 linq 查询，我有一个包含结构的列表

PostCode, Premise, Connectivity, Availability
XYZ 123,    1,       HIGH,         TRUE
XYZ 123,    2,       LOW,          TRUE
XYZ 123,    3,       LOW,          FALSE
ABC 234,    1,       HIGH,         FALSE
ABC 123,    2,       HIGH,         FALSE

我正在尝试使用 ROW_NUMBER 和分区生成我在 SQL 中完成的以下内容，但这对我来说在 c# 中实现是一个挑战。非常感谢任何帮助。

PostCode,  Connectivity, Availability
XYZ 123,         LOW,          TRUE
ABC 234,         HIGH,         FALSE

标签： c#linqpartitionrow-number

解决方案

这就是你要找的东西：

class Program
{
    static void Main(string[] args)
    {
        List<PostCode> postCodes = new List<PostCode>() {
            new PostCode() {postcode = "XYZ 123", premise = 1, connectivity = "HIGH", availability = "TRUE"},
                new PostCode() {postcode = "XYZ 123", premise = 2, connectivity = "LOW", availability = "TRUE"},
                new PostCode() {postcode = "XYZ 123", premise = 3, connectivity = "LOW", availability = "FALSE"},
                new PostCode() {postcode = "ABC 234", premise = 1, connectivity = "HIGH", availability = "FALSE"},
                new PostCode() {postcode = "ABC 123", premise = 2, connectivity = "HIGH", availability = "FALSE"}
            };

            var results = postCodes.GroupBy(x => x.postcode)
                .Select(x => x.GroupBy(y => y.premise).Select(z => new { item = z, count = z.Count() }).ToList())
                .ToList();
        }
    }
    public class PostCode
    {
        public string postcode {get; set;}
        public int premise { get; set; }
        public string connectivity { get; set; }
        public string availability { get; set; }

    }

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