如何在内存列表中分组？

Question

我有一个列表Foo。Foo 具有属性Bar和Lum. 有些Foos 具有相同的 值Bar。如何使用 lambda/linq 对我的FoosBar进行分组，以便我可以迭代每个分组的Lums？

Answer 1

迪诺,

享受：

var foos = new List<Foo> {
   new Foo{Bar = 1,Lum = 1},
   new Foo{Bar = 1,Lum = 2},
   new Foo{Bar = 2,Lum = 3},
};

// Using language integrated queries:

var q = from foo in foos
        group foo by foo.Bar into groupedFoos
        let lums = from fooGroup in groupedFoos
                   select fooGroup.Lum
        select new { Bar = groupedFoos.Key, Lums = lums };

// Using lambdas

var q = foos.GroupBy(x => x.Bar).
            Select(y => new {Bar = y.Key, Lums = y.Select(z => z.Lum)});


foreach (var group in q)
{
    Console.WriteLine("Lums for Bar#" + group.Bar);
    foreach (var lum in group.Lums)
    {
        Console.WriteLine(lum);
    }
}

要了解有关 LINQ 的更多信息，请阅读101 个 LINQ 示例