How Can I Count and Sort Duplicate Objects by ID Property Using LINQ?

Counting Duplicates by Property Using LINQ

In this scenario, you have a list of objects with an ID property. The goal is to count and group objects based on their IDs and display the results in a sorted manner, with the object with the highest count at the top.

Grouping by ID

LINQ offers the 'group by' operation to group objects based on a specified property. In your case, you want to group by the ID property. Here's how you can achieve this:

var grouped = items.GroupBy(item => item.ID);

After grouping, you'll have a collection of groups, where each group represents objects with the same ID.

Counting Items in Groups

With the groups created, you can use the 'Count()' method to count the number of objects in each group. The result is a collection of key-value pairs, where the key is the ID, and the value is the count.

var counted = grouped.Select(group => new { ID = group.Key, Count = group.Count() });

Sorting by Count

Finally, to sort the results in descending order by count, you can use the 'OrderByDescending()' method.

var sorted = counted.OrderByDescending(pair => pair.Count);

Combining the Results into a New List

To display the results in the desired format, you need to create a new list of objects containing the ID, count, and game name. You can use a combination of properties and projection to achieve this:

var results = sorted.Select(pair => new { ID = pair.ID, Count = pair.Count, GameName = items.First(item => item.ID == pair.ID).GameName });

This will give you a list of objects with the required properties.

By following these steps, you can count duplicates based on the ID property and sort the results by count using LINQ.

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