CODEWITHSUNDEEP
c#linqlambda
RenanStr
RenanStr

Reputation: 1688

How do I remove the Where condition of my lambda expression?

I'm trying to write a program that shows duplicate records to the user to correct the data or remove the duplicate rows. It works, but I had to put a Where clause in my lambda expression to get this working. How can I remove this useless clause?

Where(d => d.Id > 0) at line 22.

public class Person
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
    }

    public class Program
    {
        static void Main(string[] args)
        {
            List<Person> dt = new List<Person>();
            dt.Add(new Person() { Id = 1, Name = "MICHAEL JACKSON", Age = 50 });
            dt.Add(new Person() { Id = 2, Name = "MICHAEL JACKSON", Age = 51 });
            dt.Add(new Person() { Id = 3, Name = "JOHN LENNON", Age = 40 });
            dt.Add(new Person() { Id = 4, Name = "JOHN LENNON", Age = 41 });
            dt.Add(new Person() { Id = 5, Name = "ELVIS PRESLEY", Age = 42 });

            var duplicates = dt.AsEnumerable().GroupBy(r => r.Name).Where(gr => gr.Count() > 1).ToList();
            if (duplicates.Any())
            {
                var query = duplicates.SelectMany(c => c.Where(d => d.Id > 0)).AsQueryable();

                foreach (var item in query)
                    Console.WriteLine(String.Format("{0} - {1}", item.Name, item.Age));
            }
            else
                Console.WriteLine("No records duplicates.");

            Console.ReadLine();
        }
    }

This is just sample code, my code does a lot of other checks, but if somebody knows how to remove this clause it will be very helpful to me. I think it could impact performance.

Upvotes: 1

Views: 697

Answers (3)

lante
lante

Reputation: 7346

thats becouse duplicates is the grouped by object. try this if you only want to show the name:

var query = duplicates.Select(c => c.Key);
foreach (var item in query)
    Console.WriteLine(String.Format("{0}", item));

try this if you want to show repeated ages:

var query = duplicates.SelectMany(i => i);
foreach (var item in query)
    Console.WriteLine(String.Format("{0} - {1}", item.Name, item.Age));

Upvotes: 1

James Curran
James Curran

Reputation: 103595

This works for me.

            var query = duplicates.SelectMany(c => c).AsQueryable();

Upvotes: 1

user287107
user287107

Reputation: 9417

this here also works:

    List<Person> dt = new List<Person>();
    dt.Add(new Person() { Id = 1, Name = "MICHAEL JACKSON", Age = 50 });
    dt.Add(new Person() { Id = 2, Name = "MICHAEL JACKSON", Age = 51 });
    dt.Add(new Person() { Id = 3, Name = "JOHN LENNON", Age = 40 });
    dt.Add(new Person() { Id = 4, Name = "JOHN LENNON", Age = 41 });
    dt.Add(new Person() { Id = 5, Name = "ELVIS PRESLEY", Age = 42 });

    var duplicates = dt.GroupBy(r => r.Name).Where(gr => gr.Count() > 1).ToList();
    if (duplicates.Any())
    {

        foreach (var item in duplicates)
            Console.WriteLine(String.Format("{0} - {1}", item.Key, string.Join(",", item.Select(p => p.Age))));
    }
    else
        Console.WriteLine("No records duplicates.");

    Console.ReadLine();

Upvotes: 2

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