c# - 如何在不更改其类型的情况下订购 IGrouping？

Question

我有一个 IGrouping 类型的对象，想在不更改对象类型的情况下对组内的元素进行排序。
换句话说，我有

var tmp = group.OrderBy(x => x);

与 group类型 IGrouping<int, someanonymousclass>我想要 tmp类型为 IGrouping<int, someanonymousclass>

一种解决方法是将其更改为字典或新的匿名类，但我希望 tmp 的类型明确为 IGrouping<int, someanonymousclass> .

换句话说:我想对 IGrouping<int, someanonymousclass> 的元素进行排序目的。如果我使用 OrderBy它改变了 group 的类型至 IOrderedEnumerable我无法访问 group.Key了。我怎样才能维持 group 的类型？

示例:

var states = SimulationPanel.innerPanel.Children.OfType<StateBar>().Where(x => x.isSensorState())
                .GroupBy(x => (SensorElement)x.BauplanElement,
                         x => new
                         {
                             Start = (decimal)(x.Margin.Left / SimulationPanel.Zoom),
                             Width = (decimal)(x.Width / SimulationPanel.Zoom),
                             State = x.State
                         });

var group = states.First();
var tmp = group.OrderBy(x => x.Start);
var key = tmp.Key;    //This does not work, because tmp is not of type IGrouping

我知道我可以使用 OrderBy分组前。不过，我不想那样做。

Answer 1

如果您可以，请提前下单，例如

var states = SimulationPanel.innerPanel
       .Children
       .OfType<StateBar>()
       .Where(x => x.isSensorState())
       .OrderBy(x => (decimal)(x.Margin.Left / SimulationPanel.Zoom))
       .GroupBy(...);

(或者在 Select 之前放一个 OrderBy 并使 GroupBy 更简单。)

如果你真的需要这个，你可以自己写 IGrouping<TKey, TElement>对元素进行排序并将它们保留在列表中的实现和扩展方法:

public static class GroupExtensions
{
    public static IGrouping<TKey, TElement> OrderGroupingBy<TKey, TElement, TOrderKey>
        (this IGrouping<TKey, TElement> grouping,
         Func<TElement, TOrderKey> orderKeySelector)
    {
        return new GroupingImpl<TKey, TElement>
            (grouping.Key, grouping.OrderBy(orderKeySelector));
    }

    private class GroupingImpl<TKey, TElement> : IGrouping<TKey, TElement>
    {
        private readonly TKey key;
        private readonly List<TElement> elements;

        internal GroupingImpl(TKey key, IEnumerable<TElement> elements)
        {
            this.key = key;
            this.elements = elements.ToList();
        }

        public TKey Key { get { return key; } }

        public IEnumerator<TElement> GetEnumerator()
        {
            return elements.GetEnumerator();
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return GetEnumerator();
        }
    }
}