CODEWITHSUNDEEP
c#listmergeduplicates
Kiquenet
Kiquenet

Reputation: 14976

How to merge 2 List<T> and removing duplicate values from it in C#

I have two lists List that I need to combine in third list and remove duplicate values from that lists

A bit hard to explain, so let me show an example of what the code looks like and what I want as a result, in sample I use int type not ResultAnalysisFileSql class.

first_list = [1, 12, 12, 5]

second_list = [12, 5, 7, 9, 1]

The result of combining the two lists should result in this list: resulting_list = [1, 12, 5, 7, 9]

You'll notice that the result has the first list, including its two "12" values, and in second_list has an additional 12, 1 and 5 value.

ResultAnalysisFileSql class

[Serializable]
    public partial class ResultAnalysisFileSql
    {
        public string FileSql { get; set; }

        public string PathFileSql { get; set; }

        public List<ErrorAnalysisSql> Errors { get; set; }

        public List<WarningAnalysisSql> Warnings{ get; set; }

        public ResultAnalysisFileSql()
        {

        }

        public ResultAnalysisFileSql(string fileSql)
        {
            if (string.IsNullOrEmpty(fileSql)
                || fileSql.Trim().Length == 0)
            {
                throw new ArgumentNullException("fileSql", "fileSql is null");
            }

            if (!fileSql.EndsWith(Utility.ExtensionFicherosErrorYWarning))
            {
                throw new ArgumentOutOfRangeException("fileSql", "Ruta de fichero Sql no tiene extensión " + Utility.ExtensionFicherosErrorYWarning);
            }

            PathFileSql = fileSql;
            FileSql = ObtenerNombreFicheroSql(fileSql);
            Errors = new List<ErrorAnalysisSql>();
            Warnings= new List<WarningAnalysisSql>();
        }

        private string ObtenerNombreFicheroSql(string fileSql)
        {
            var f = Path.GetFileName(fileSql);
            return f.Substring(0, f.IndexOf(Utility.ExtensionFicherosErrorYWarning));
        }


        public override bool Equals(object obj)
        {
            if (obj == null)
                return false;
            if (!(obj is ResultAnalysisFileSql))
                return false;

            var t = obj as ResultAnalysisFileSql;
            return t.FileSql== this.FileSql
                && t.PathFileSql == this.PathFileSql
                && t.Errors.Count == this.Errors.Count
                && t.Warnings.Count == this.Warnings.Count;
        }


    }

Any sample code for combine and removing duplicates ?

Upvotes: 217

Views: 223146

Answers (6)

Joel Wiklund
Joel Wiklund

Reputation: 1875

To elaborate on fateme maddahi's answer.

If list2 contains two or more items with duplicate Number properties you will get an exception with ToDictionary:

[System.ArgumentException: An item with the same key has already been added.]

To avoid this, use this instead:

var dict = list2
    .GroupBy(p => p.Number, StringComparer.OrdinalIgnoreCase)
    .ToDictionary(g => g.Key, g => g.First(), StringComparer.OrdinalIgnoreCase);

foreach (var person in list1)
{
        dict[person.Number] = person;
}
var merged = dict.Values.ToList();

Source

Upvotes: 0

Adriaan Stander
Adriaan Stander

Reputation: 166336

Have you had a look at Enumerable.Union

This method excludes duplicates from the return set. This is different behavior to the Concat method, which returns all the elements in the input sequences including duplicates.

List<int> list1 = new List<int> { 1, 12, 12, 5};
List<int> list2 = new List<int> { 12, 5, 7, 9, 1 };
List<int> ulist = list1.Union(list2).ToList();

// ulist output : 1, 12, 5, 7, 9

Upvotes: 415

user57508
user57508

Reputation:

why not simply eg

var newList = list1.Union(list2)/*.Distinct()*//*.ToList()*/;

oh ... according to the documentation you can leave out the .Distinct()

This method excludes duplicates from the return set

Upvotes: 38

fateme maddahi
fateme maddahi

Reputation: 476

Union has not good performance : this article describe about compare them with together

var dict = list2.ToDictionary(p => p.Number);
foreach (var person in list1)
{
        dict[person.Number] = person;
}
var merged = dict.Values.ToList();

Lists and LINQ merge: 4820ms
Dictionary merge: 16ms
HashSet and IEqualityComparer: 20ms
LINQ Union and IEqualityComparer: 24ms

Upvotes: 34

Faizan S.
Faizan S.

Reputation: 8644

    List<int> first_list = new List<int>() {
        1,
        12,
        12,
        5
    };

    List<int> second_list = new List<int>() {
        12,
        5,
        7,
        9,
        1
    };

    var result = first_list.Union(second_list);

Upvotes: 13

Robert Jeppesen
Robert Jeppesen

Reputation: 7877

Use Linq's Union:

using System.Linq;
var l1 = new List<int>() { 1,2,3,4,5 };
var l2 = new List<int>() { 3,5,6,7,8 };
var l3 = l1.Union(l2).ToList();

Upvotes: 18

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