C# 如何对按其他字段分组的列表进行排序

我有一个事件对象列表：

class Event {
    private int eventId;
    private int categoryId;
    private int eventOrder;
}

按eventOrder字段排序后，结果如下：

Event (eventId = 11, categoryId = 3, eventOrder = 1) 
Event (eventId = 44, categoryId = 2, eventOrder = 2)
Event (eventId = 33, categoryId = 3, eventOrder = 3)
Event (eventId = 55, categoryId = 4, eventOrder = 4)
Event (eventId = 22, categoryId = 1, eventOrder = 5)

---

如果我按eventOrder排序，然后按categoryId排序，结果是：

Event (eventId = 55, categoryId = 4, eventOrder = 4) 
Event (eventId = 11, categoryId = 3, eventOrder = 1)  
Event (eventId = 33, categoryId = 3, eventOrder = 3) 
Event (eventId = 22, categoryId = 2, eventOrder = 5) 
Event (eventId = 44, categoryId = 1, eventOrder = 2)

我需要尊重较低的事件顺序来安排事件，但类别需要是连续的，预期结果：

Event (eventId = 11, categoryId = 3, eventOrder = 1) 
Event (eventId = 33, categoryId = 3, eventOrder = 3)
Event (eventId = 44, categoryId = 1, eventOrder = 2)
Event (eventId = 55, categoryId = 4, eventOrder = 4)
Event (eventId = 22, categoryId = 2, eventOrder = 5)

总之：事件需要按类别中最低的事件顺序排序。

---

我可以用比较器实现吗？

您必须按

类别ID

进行分组，然后按每组中最小的

事件顺序进行排序。我还在
categoryId
上添加了一个二级排序，但这仅在
eventOrder
不唯一时才需要。排序后，您可以使用
选择many
取消分组

var eventList = new List<Event>
{
    new Event {eventId = 11, categoryId = 3, eventOrder = 1},
    new Event {eventId = 44, categoryId = 2, eventOrder = 2},
    new Event {eventId = 33, categoryId = 3, eventOrder = 3},
    new Event {eventId = 55, categoryId = 4, eventOrder = 4},
    new Event {eventId = 22, categoryId = 1, eventOrder = 5}
};
var sortedResult = eventList.GroupBy(x => x.categoryId)
    .OrderBy(x => x.Min(y => y.eventOrder))
    .ThenBy(x => x.Key)
    .SelectMany(x => x)
    .ToList();

foreach (var item in sortedResult)
  Console.WriteLine($"Event (eventId = {item.eventId}, categoryId = {item.categoryId}, eventOrder = {item.eventOrder})");

您可以使用Linq
OrderByDescending
和
ThenBy
来实现这一点。我编辑了问题以澄清问题，我无法在按事件顺序对ir排序后按类别ID对列表进行排序，我只需移动匹配类别ID的位置。如果我按事件顺序排序，然后按类别ID排序，结果是：
Event（eventId=55，categoryId=4，eventOrder=4）
事件（eventId=11，categoryId=3，eventOrder=1）
事件（eventId=33，categoryId=3，eventOrder=3）
事件（eventId=22，categoryId=2，eventOrder=5）

事件（eventId=44，categoryId=1，eventOrder=2）

我想我现在明白你的问题了。很抱歉将其标记为重复。

Event (eventId = 11, categoryId = 3, eventOrder = 1)
Event (eventId = 33, categoryId = 3, eventOrder = 3)
Event (eventId = 44, categoryId = 2, eventOrder = 2)
Event (eventId = 55, categoryId = 4, eventOrder = 4)
Event (eventId = 22, categoryId = 1, eventOrder = 5)