CODEWITHSUNDEEP
c#listforeachcombinations
Asaf
Asaf

Reputation: 91

Manipulation on all list items options for n lists in c#

I'd like to split my data to lists by an attribute's value and check all the combination options between the lists' items. My problems are that I don't know how many list I'll get and if there is a better way to do that beside this way:

var a = Data.Descendants("value").Where(x => x.Attribute("v").Value == "1").ToList(); var b = Data.Descendants("value").Where(x => x.Attribute("v").Value == "2").ToList(); var c = Data.Descendants("value").Where(x => x.Attribute("v").Value == "3").ToList();

foreach (var tempA in a) { foreach (var tempB in b) { foreach (var tempC in c) { DO SOMETHING; } } }

EDIT: I'd like to check my items from one data source (var items = new List<string>{"1","1","2","3","2","1","3","3","2"})

Now I'd like to split this list to 3 lists (list a = "1","1","1" - list b = "2","2","2" - list c = "3","3","3")

In this step what I'm trying to do is to check all the combination from one item in one list to the other items in the other lists.

a[0] with b[0] c[0]
a[0] with b[0] c[1]
a[0] with b[0] c[2]
a[0] with b[1] c[0]
.
.
b[1] with a[2] c[2]
.
.

Thanks!

Upvotes: 2

Views: 229

Answers (3)

terrybozzio
terrybozzio

Reputation: 4532

You can do this,following the line of thinking of romoku and chrisC

//new list of lists to hold new information.
List<List<Descendants>> NewList = new List<List<Descendants>>();

foreach (var item in Data.Descendants.GroupBy(x => x.Attribute("v").Value))
{
     NewList.Add(item.ToList());
}

For your new edit list of Strings this will do it

List<List<string>> NewList = new List<List<string>>();

foreach (var item in OriginalList.GroupBy(x => x))
{
      NewList.Add(item.ToList());
}

Upvotes: 0

Dustin Kingen
Dustin Kingen

Reputation: 21255

You can use GroupBy to group your elements. Then you can create combinations using Linq.

var grouping = Data.Descendants("value")
                   .GroupBy(x => x.Attribute("v").Value);

var combinations grouping.SelectMany(x =>
                              grouping.Select(y =>
                                  new { Group = x, Combination = y }));

foreach(var c in combinations)
{
    //Do Something
}

e.g.

public class Pair
{
    public string A { get; set; }
    public string B { get; set; }
}

var pairs = new List<Pair>();
pairs.Add(new Pair { A = "1", B = "2" });
pairs.Add(new Pair { A = "1", B = "3" });
pairs.Add(new Pair { A = "1", B = "4" });
pairs.Add(new Pair { A = "2", B = "1" });
pairs.Add(new Pair { A = "2", B = "2" });
pairs.Add(new Pair { A = "2", B = "3" });

var grouping = pairs.GroupBy(x => x.A);

var combinations = grouping.SelectMany(x =>
                                grouping.Select(y =>
                                    new { Group = x, Combination = y }));

Groupings result

Upvotes: 0

ChrisC
ChrisC

Reputation: 1171

Could you try using the LINQ GroupBy method? Some examples are here:

LINQ GroupBy examples

Upvotes: 0

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