LINQ操作List<T>

LINQ操作List<T>主要包括：

1.筛选

List<string> stcdList = stcdArray.ToList<string>()

                .FindAll(new Predicate<string>(stcd => stcd.Contains("stcd_")))

                .Select(stcd => stcd.Substring())

                .ToList<string>();

2.拼接

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

string sg_font_details = suggestion.Aggregate((s1, s2) => string.Format("{0},{1}", s1, s2)).ToString();

3.分组统计

public class HomeStat

    {

        public string adnm { get; set; }

        public string ProCount { get; set; }

        public string countCompare { get; set; }

        public string perCount { get; set; }

        public string dayCount { get; set; }

        public string perDayCount { get; set; }

    }

List<HomeStat> chsList = new List<HomeStat>() {... };

var query = hsList.GroupBy(t => t.adnm).Select(p => new

                    {

                        adnm = p.Key,

                        dayCount = p.Sum(x => double.Parse(x.dayCount)),

                        proCount = p.Select(x => x.projectID).Distinct().Count(),

                        perCount = p.Sum(x => double.Parse(x.perCount)),

                        perDayCount = p.Sum(x => double.Parse(x.perDayCount))

                    });

4.分组拼接

public class Service

    {

        public string Month { get; set; }

        public string Content { get; set; }

    }

List<Service> serList = new List<Service>(){...};

var query = serList.GroupBy(t => t.Month).Select(g => g.Aggregate((s1, s2) =>

                new Service { Month = g.Key, Content = s1.Content + "," + s2.Content }))

                .OrderByDescending(t => t.Month);