I have a list of items
I want to shove them back into a list like so which also means I want to sort by the highest number of duplicates.
Let me know how I can do this with LINQ and C#.
Thanks All
EDIT 2 Showing Code:
List<game> inventory = new List<game>();
drinkingforDataContext db = new drinkingforDataContext();
foreach (string item in tbTitle.Text.Split(' '))
{
List<game> getItems = (from dfg in db.drinkingfor_Games
where dfg.game_Name.Contains(tbTitle.Text)
select new game
{
gameName = dfg.game_Name,
gameID = Boomers.Utilities.Guids.Encoder.EncodeURLs(dfg.uid)
}).ToList<game>();
for (int i = 0; i < getItems.Count(); i++)
{
inventory.Add(getItems[i]);
}
}
var items = (from xx in inventory
group xx by xx into g
let count = g.Count()
orderby count descending
select new
{
Count = count,
gameName = g.Key.gameName,
gameID = g.Key.gameID
});
lvRelatedGames.DataSource = items;
lvRelatedGames.DataBind();
This query displays these results:
It gives me the count and name, but it doesn't give me the ID of the game....
It should display:
You can use "group by" + "orderby". See LINQ 101 for details
var list = new List<string> {"a", "b", "a", "c", "a", "b"};
var q = from x in list
group x by x into g
let count = g.Count()
orderby count descending
select new {Value = g.Key, Count = count};
foreach (var x in q)
{
Console.WriteLine("Value: " + x.Value + " Count: " + x.Count);
}
In response to this post (now deleted):
If you have a list of some custom objects then you need to use custom comparer or group by specific property.
Also query can't display result. Show us complete code to get a better help.
Based on your latest update:
You have this line of code:
group xx by xx into g
Since xx is a custom object system doesn't know how to compare one item against another. As I already wrote, you need to guide compiler and provide some property that will be used in objects comparison or provide custom comparer. Here is an example:
Note that I use Foo.Name as a key - i.e. objects will be grouped based on value of Name property.
There is one catch - you treat 2 objects to be duplicate based on their names, but what about Id ? In my example I just take Id of the first object in a group. If your objects have different Ids it can be a problem.
//Using extension methods
var q = list.GroupBy(x => x.Name)
.Select(x => new {Count = x.Count(),
Name = x.Key,
ID = x.First().ID})
.OrderByDescending(x => x.Count);
//Using LINQ
var q = from x in list
group x by x.Name into g
let count = g.Count()
orderby count descending
select new {Name = g.Key, Count = count, ID = g.First().ID};
foreach (var x in q)
{
Console.WriteLine("Count: " + x.Count + " Name: " + x.Name + " ID: " + x.ID);
}
Slightly shorter version using methods chain:
var list = new List<string> {"a", "b", "a", "c", "a", "b"};
var q = list.GroupBy(x => x)
.Select(g => new {Value = g.Key, Count = g.Count()})
.OrderByDescending(x=>x.Count);
foreach (var x in q)
{
Console.WriteLine("Value: " + x.Value + " Count: " + x.Count);
}
The other solutions use GroupBy. GroupBy is slow (it holds all the elements in memory) so I wrote my own method CountBy:
public static Dictionary<TKey,int> CountBy<TSource,TKey>(this IEnumerable<TSource> source, Func<TSource,TKey> keySelector)
{
var countsByKey = new Dictionary<TKey,int>();
foreach(var x in source)
{
var key = keySelector(x);
if (!countsByKey.ContainsKey(key))
countsByKey[key] = 0;
countsByKey[key] += 1;
}
return countsByKey;
}
Here is the complete programme please check this
static void Main(string[] args)
{
List<string> li = new List<string>();
li.Add("Ram");
li.Add("shyam");
li.Add("Ram");
li.Add("Kumar");
li.Add("Kumar");
var x = from obj in li group obj by obj into g select new { Name = g.Key, Duplicatecount = g.Count() };
foreach(var m in x)
{
Console.WriteLine(m.Name + "--" + m.Duplicatecount);
}
Console.ReadLine();
}
You can also do Dictionary:
var list = new List<string> { "a", "b", "a", "c", "a", "b" };
var result = list.GroupBy(x => x)
.ToDictionary(y=>y.Key, y=>y.Count())
.OrderByDescending(z => z.Value);
foreach (var x in result)
{
Console.WriteLine("Value: " + x.Key + " Count: " + x.Value);
}
Slightly shorter version using methods chain:
var list = new List<string> {"a", "b", "a", "c", "a", "b"};
var q = list.GroupBy(x => x)
.Select(g => new {Value = g.Key, Count = g.Count()})
.OrderByDescending(x=>x.Count);
foreach (var x in q)
{
Console.WriteLine("Value: " + x.Value + " Count: " + x.Count);
}
You can also do Dictionary:
var list = new List<string> { "a", "b", "a", "c", "a", "b" };
var result = list.GroupBy(x => x)
.ToDictionary(y=>y.Key, y=>y.Count())
.OrderByDescending(z => z.Value);
foreach (var x in result)
{
Console.WriteLine("Value: " + x.Key + " Count: " + x.Value);
}
Slightly shorter version using methods chain:
var list = new List<string> {"a", "b", "a", "c", "a", "b"};
var q = list.GroupBy(x => x)
.Select(g => new {Value = g.Key, Count = g.Count()})
.OrderByDescending(x=>x.Count);
foreach (var x in q)
{
Console.WriteLine("Value: " + x.Value + " Count: " + x.Count);
}
Here is the complete programme please check this
static void Main(string[] args)
{
List<string> li = new List<string>();
li.Add("Ram");
li.Add("shyam");
li.Add("Ram");
li.Add("Kumar");
li.Add("Kumar");
var x = from obj in li group obj by obj into g select new { Name = g.Key, Duplicatecount = g.Count() };
foreach(var m in x)
{
Console.WriteLine(m.Name + "--" + m.Duplicatecount);
}
Console.ReadLine();
}
Source: Stackoverflow.com