CODEWITHSUNDEEP
c#.net
Bears
Bears

Reputation: 41

How to compare all objects to each other.?

I want to compare two objects with all possible variations. How can I do that.

var _entries = new List<string>();

_entries.Add("Awesom");
_entries.Add("Awesom");
_entries.Add("Awesom");
_entries.Add("Awesom");

int count = 0;

for (int i = 1; i < _entries.Count; i++)
{
    if (_entries[i].Equals(_entries[i - 1]))
    {
        count++;
    }
}

Console.Write(count);
Console.ReadLine();

This one compares in sequential order but it should compare with every possible scenario.

The expected result should be 4 because there are 4 same objects in array.

Upvotes: 2

Views: 217

Answers (2)

Gaurav Mathur
Gaurav Mathur

Reputation: 849

When you say This one compares in sequential order but it should compare with every possible scenario. I believe you are expecting value of count = 16. As by comparing with every possible values you'll have 16 combinations and as all the values are equal you'll get count as 16.

            var _entries = new List<string>();

        _entries.Add("Awesom");
        _entries.Add("Awesom");
        _entries.Add("Awesom");
        _entries.Add("Awesom");

        var query = from e1 in _entries
                    from e2 in _entries
                    where e1 == e2
                    select $"{e1} x {e2}";
        var count = query.Count();

Try printing values of query variable and you'll see all combinations.

Upvotes: 0

Dmitrii Bychenko
Dmitrii Bychenko

Reputation: 186668

I suggest using Linq, GroupBy: 

using System.Linq;

...

// No Sequential Order test
var _entries = new List<string>() {
   "Awesom",
   "Bar",
   "Awesom",
   "Awesom",
   "Foo",
   "Awesom",
   "Bar",   
};

int count = _entries
  .GroupBy(item => item)    
  .Sum(group => group.Count() - 1);

with a help of GroupBy we obtain 3 groups:

4 items of "Awesom"
1 items of "Foo" 
2 items of "Bar"

then we can just Count items in each group and Sum them: (4 - 1) + (1 - 1) + (2 - 1) == 4 duplicates overall.

Upvotes: 5

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