Linq独特计数

Question

I have some data returned as the follow:

Model { Guid Id }

and I have an int of the total items, int totalCount .

I am trying to get the distinct count from the data that were returned as Category 1, and have the total item minus the count from Category 1 to be Category 2.

I have the following linq to get the distinct count for Category 1, but how do I add the count for Category 2 into the IEnumerable?

var result = data.
    GroupBy(x => x.Id).
    Select(x => new { Category = "1", Value = x.Select(v => v.Id).Distinct().Count() }).
    GroupBy(x => x.Category).
    Select(x => new Item { Category = x.Key, Value = x.Sum(y => y.Value) });

and the Item Class have 2 members: string for Category and decimal for Value.

Thanks!

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Edit: So I have the follow data IEnumerable<Model> data , and it contains the following data:

{ Id: 1 }
{ Id: 2 }
{ Id: 2 }
{ Id: 1 }
{ Id: 3 }
{ Id: 4 }

and totalCount = 10.

I would like to get the distinct count of Id from data, which is 4 in this case, as category 1, and totalCount - distinct item to be category 2. So for the result I will have a IEnumerable of Item to have the following:

{ Category: "1", Value: 4 }, { Category: "2", Value: 6 }

For now my linq statement only return { Category: "1", Value: 4 } , and I have no idea what to do next.

Answer 1

Your question is not very clear, but I think this is what you want:

int totalCount = data.Count();
int distinctCount = data.Select(x => x.Id).Distinct().Count();
List<Item> result = new List<Item>
{
    new Item() { Category = "1", Value = distinctCount },
    new Item() { Category = "2", Value = totalCount - distinctCount },
};

Answer 2

Do you need two objects at the end of the day, or can it just be part of one return? You could just do:

var result = data.
    GroupBy(x => x.Id).
    Select(x => new { 
       DistinctCount = x.Select(v => v.Id).Distinct().Count(),
       TotalCount = data.Count()
    });

This or something similar would probably work.

Answer 3

I use the data structure to face the situation.

Dictionary< string, List< YOUR_TYPE >> dictionary = new Dictionary<string, List< YOUR_TYPE >> ();

We can get different keys from source.

var keys = YOUR_DATA_SOURCE.Select(item => item.YOUR_KEY_NAME ).Distinct();

Just like SQL : "SELECT DISTINCT YOUR_KEY_NAME FROM YOUR_DATA_SOURCE".

foreach (var key in keys) {
    var list = new List< YOUR_TYPE > ();
    list.AddRange (dataSource.Where (x => x.YOUR_Filter_Property == YOUR_KEY_NAME ).ToList ());

    dictionary.Add (key, list);
}

Then we can use Dictionary's default features, like "ContainKey", "Keys" to help us.