在C＃中，如何通过单独的int数组对对象集合进行排序？

Question

I have a collection of Person objects and a Person object has an id property.

 var peopleList = new List<Person>();
 peopleList .Add(new Person(){Name = Joe, Id = 30};
 peopleList .Add(new Person(){Name = Tom, Id = 22};
 peopleList .Add(new Person(){Name = Jack, Id = 62};

I now have an array of integers that represents the ordering that i want to display the array

 var list = new List<int>();
 list.Add(22);
 list.Add(62);
 list.Add(30);

what is the correct way of sorting the PeopleList collection by the List array? so I get an ordering of:

Tom, Jack, Joe

Answer 1

Create a lookup of ids to person objects:

var peopleLookup = peopleList.ToDictionary(person => person.Id);

Then you can go through your list of IDs, mapping each to a person:

var query = list.Select(id => peopleLookup[id]);

Answer 2

You can use list.IndexOf(Id) . Use LINQ's OrderBy to create a new list

var sorted = peopleList.OrderBy(x => list.IndexOf(x.Id)).ToList();

Or use List<T>.Sort to reorder the list itself

peopleList.Sort((x, y) => list.IndexOf(x.Id).CompareTo(list.IndexOf(y.Id)));

Answer 3

Might be slow if collection is huge, but this works.

var peopleList = new List<Person>();
peopleList.Add(new Person() { Name = "Joe", Id = 30 });
peopleList.Add(new Person() { Name = "Tom", Id = 22 });
peopleList.Add(new Person() { Name = "Jack", Id = 62 });

var list = new List<int>();
list.Add(22);
list.Add(62);
list.Add(30);

peopleList.Sort((x, y) => list.IndexOf(x.Id).CompareTo(list.IndexOf(y.Id)));