Question

我设计的方法接受List<Bar>，并返回<List>BarGroup，按Bar.barName分组。我的猜测是我需要在List.Add中使用Aggregate，但我对lambdas和Linq的语法还是比较新的！

到目前为止我的代码：

public class BarGroup
{
   public string barName;
   public List<Bar> barList;
}

public class Bar
{
   public string barName;
   public string fooDetails;

   public Bar(string b, string f)
   {
       this.barName = b;
       this.fooDetails = f;
   }
}

void Main()
{
    Bar bar1 = new Bar("BarGroup1","Bar1");
    Bar bar2 = new Bar("BarGroup1","Bar2");
    Bar bar3 = new Bar("BarGroup2", "Bar3");
    Bar bar4 = new Bar("BarGroup2", "Bar4");

    List<Bar> bars = new List<Bar> { bar1, bar2, bar3, bar4 };

    var barGrouped = from b in bars
                group b by b.barName into g
                select new BarGroup()
                {
                    barName = g.Key, 
                    barList = bars
                };

    Console.WriteLine(barGrouped);
}

当我在LinqPad中尝试这个时，我得到以下结果：

IEnumerable<BarGroup> (2 items)
barName     barList 
BarGroup1   List<Bar> (4 items)
            barName    fooDetails 
            BarGroup1  Bar1 
            BarGroup1  Bar2 
            BarGroup2  Bar3 
            BarGroup2  Bar4 

BarGroup2   List<Bar> (4 items)
            barName    fooDetails 
            BarGroup1  Bar1 
            BarGroup1  Bar2 
            BarGroup2  Bar3 
            BarGroup2  Bar4

但我正在寻找的是：

IEnumerable<BarGroup> (2 items)
barName     barList 
BarGroup1   List<Bar> (4 items)
            barName    fooDetails 
            BarGroup1  Bar1 
            BarGroup1  Bar2 

BarGroup2   List<Bar> (4 items)
            barName    fooDetails 
            BarGroup2  Bar3 
            BarGroup2  Bar4

我认为Linq是这种分裂的最佳选择，但我对任何其他完成相同任务的方法持开放态度。

Answer 1

尝试

var barGrouped = from b in bars
            group b by b.barName into g
            select new BarGroup()
            {
                barName = g.Key, 
                barList = g.ToList()
            };

组IEnumerable<Bar>满足分组标准。 bars是原始集合，这就是为什么在你的BarGroups中你可以获得所有项目。

Linq to Objects Sum to List

1 个答案: