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How to find not matching records in Generic List in C# [duplicate]

This question already has answers here:
Using Linq Except not Working as I Thought
(5 answers)
Closed 4 years ago.
I have two Generic List object, I want to get records which are not matching in second Generic list object. Below is my code. But it returning all records.
I want to ignore matching record in first list.
public class CuratedIncludeUid
{
public string type { get; set; }
public string uid { get; set; }
}
List<CuratedIncludeUid> newUids = new List<CuratedIncludeUid>();
newUids.Add(new CuratedIncludeUid { type = "series", uid = "600" });
List<CuratedIncludeUid> liExistingUids = new List<CuratedIncludeUid>();
liExistingUids.Add(new CuratedIncludeUid { type = "series", uid = "600" });
liExistingUids.Add(new CuratedIncludeUid { type = "series", uid = "200" });
var ied = liExistingUids.Except(newUids).ToList(); ;
foreach (var row in ied)
{
Console.WriteLine("Uid:" + row.uid + "type:" + row.type);
}
Console.Read();
I am getting Output as below
Uid:600type:series
Uid:200type:series
**My expected output as below
Uid:200type:series**

Either override Equals and GetHashCode
public class CuratedIncludeUid
{
public string type { get; set; }
public string uid { get; set; }
protected bool Equals(CuratedIncludeUid other)
{
return string.Equals(type, other.type) && string.Equals(uid, other.uid);
}
public override bool Equals(object obj)
{
if (ReferenceEquals(null, obj)) return false;
if (ReferenceEquals(this, obj)) return true;
return Equals((CuratedIncludeUid) obj);
}
public override int GetHashCode()
{
unchecked
{
return ((type != null ? type.GetHashCode() : 0) * 397) ^ (uid != null ? uid.GetHashCode() : 0);
}
}
}
Or passing an IEqualityComparer to Except
public class CuratedIncludeUidEqualityComparer : IEqualityComparer<CuratedIncludeUid>
{
public bool Equals(CuratedIncludeUid x, CuratedIncludeUid y)
{
if (ReferenceEquals(x, y)) return true;
if (ReferenceEquals(x, null) || ReferenceEquals(y, null)) return false;
return string.Equals(x.type, y.type) && string.Equals(x.uid, y.uid);
}
public int GetHashCode(CuratedIncludeUid obj)
{
unchecked
{
return ((obj.type != null ? obj.type.GetHashCode() : 0) * 397) ^ (obj.uid != null ? obj.uid.GetHashCode() : 0);
}
}
}
var ied = liExistingUids.Except(newUids, new CuratedIncludeUidEqualityComparer()).ToList();

Either, you can implement Equals and GetHashCode or IEqualityComparer, or you can also do the following:
With All:
var ied = liExistingUids.Except(newUids).ToList();
liExistingUids
.Where(x => newUids.All(y => y.type != x.type && y.series != x.series))
.ToList();
With Any:
liExistingUids
.Where(x => !newUids.Any(y => y.type == x.type && y.series == x.series))
.ToList();

Sort List<T> with integer property using C#

I want to sort my List, where T is Products.
The List may contains elememts with duplicate ReportSeqId. I want to sort it according to ReportSeqId.
But the criteria is that if the ReportSeqId = 0 then it should come last.
INPUT :
new ilistProd<Products>()
{
new Products(0, Report1, SSR),
new Products(2, Report2, SBO),
new Products(0, Report3, PST),
new Products(3, Report4, ABR),
new Products(1, Report5, OSS),
new Products(0, Report6, TCP),
}
OUTPUT:
new ilistProd<Products>()
{
new Products(1, Report5, OSS),
new Products(2, Report2, SBO),
new Products(3, Report4, ABR),
new Products(0, Report3, PST),
new Products(0, Report6, TCP),
new Products(0, Report1, SSR)
}
Below is my code :
public class Products
{
//ctor
public SDVar(int xiReportSeqId, string xiReportName, string xiProduct)
{
this.ReportSeqId = xiReportSeqId;
this.ReportName = xiReportName;
this.Product = xiProduct;
}
public int ReportSeqId {get; set;}
public string ReportName {get; set;}
public string Product {get; set;}
}
public class SDVar
{
//ctor
public SDVar()
{
}
public void DoSort(ref List<Products> ilistProd)
{
ilistProd.Sort(delegate(Products x, Products y)
{
if (x.ReportSeqId == 0)
{
if (y.ReportSeqId == 0)
{
return 0;
}
return -1;
}
return x.ReportSeqId.CompareTo(y.ReportSeqId);
}
}
}

Try this
list.Sort(delegate(Products x, Products y)
{
if(x.ReportSeqId == 0)
return 1;
if(y.ReportSeqId == 0)
return -1;
return x.ReportSeqId.CompareTo(y.ReportSeqId);
});

Normally my preferred solution would be to add an extra property (e.g. SortIndex) which can be used in either Linq, or in a sort delegate (where id 0 would return an int.maxvalue), but to get the existing code to work, you should do an extra check to see of the second id is 0, if the first id is not:
if (x.ReportSeqId == 0)
{
if (y.ReportSeqId == 0)
{
return 0;
}
return 1;
}
else if (y.ReportSeqId == 0)
return -1;
return x.ReportSeqId.CompareTo(y.ReportSeqId);

Another way is to implement IComparable
public class Product : IComparable<Product>
{
private int ReportSeqId = 0;
public int CompareTo(Product other)
{
if (ReportSeqId == 0 || other == null) return 1;
if (other.ReportSeqId == 0) return - 1;
return ReportSeqId - other.ReportSeqId;
}
}

Using LINQ:
products = products.OrderBy(p => p.ReportSeqId == 0 ? Int32.MaxValue : p.ReportSeqId).ToList();

Comparison of Objects (Multiple Levels)

I want to create objects with 5 properties and each properties has 2 attributes. After that, I compare the objects if they are same, they will be grouped in same category.
Here is the code:
Item.cs
public class Item
{
public Item()
{
}
public SortProperty SortPropA { get; set; }
public SortProperty SortPropB { get; set; }
public SortProperty SortPropC { get; set; }
public SortProperty SortPropD { get; set; }
public SortProperty SortPropE { get; set; }
public string Name { get; set; }
public string Desc { get; set; }
}
SortProperty.cs
public class SortProperty : IEquatable<SortProperty>
{
public string PartName { get; set; }
public string GroupabilityID { get; set; }
public SortProperty()
{
}
public override int GetHashCode()
{
int hash = 19;
hash = hash * 31 + (GroupabilityID == null ? 0 : GroupabilityID.GetHashCode());
hash = hash * 31 + (PartName == null ? 0 : PartName.GetHashCode());
return hash;
}
public bool Equals(SortProperty obj)
{
return (obj == null) ?
false : (GroupabilityID == obj.GroupabilityID) || (PartName == obj.PartName);
}
public override bool Equals(Object obj)
{
SortProperty itemobj = obj as SortProperty;
return itemobj == null ? false : Equals(itemobj);
}
}
Program.cs (main class to test the coding)
class Program
{
static void Main(string[] args)
{
Item objA = new Item();
Item objB = new Item();
// ------ Object A
objA.Name = "Card1";
objA.Desc = "Product Test A";
//Property A
objA.SortPropA = new SortProperty();
objA.SortPropA.PartName = "Plastic A";
objA.SortPropA.GroupabilityID = "A1";
//Property B
objA.SortPropB = new SortProperty();
objA.SortPropB.PartName = "Color Green";
objA.SortPropB.GroupabilityID = "B2";
//Property C
objA.SortPropC = new SortProperty();
objA.SortPropC.PartName = "Visa";
objA.SortPropC.GroupabilityID = "C1";
// ------ Object B
objB.Name = "Card2";
objB.Desc = "Product Test B";
//Property A
objB.SortPropA = new SortProperty();
objB.SortPropA.PartName = "Plastic B";
objB.SortPropA.GroupabilityID = "A2";
//Property B
objB.SortPropB = new SortProperty();
objB.SortPropB.PartName = "Color Lime";
objB.SortPropB.GroupabilityID = "B1";
//Property C
objB.SortPropC = new SortProperty();
objB.SortPropC.PartName = "Visa";
objB.SortPropC.GroupabilityID = "C1";
bool isEqual = objA.Equals(objB);
if (isEqual == true)
Console.WriteLine("Is same");
else
Console.WriteLine("Is different");
Console.ReadKey();
}
}
The result should return true because there is a same property between objA and objB (SortPropc) but it return false.
I believe I have miss some logic part and I have sitting on chair for 4 hours but couldn't fix it. Can anyone please solve it?

The result should return true because there is a same property between objA and objB (SortPropc) but it return false.
You have just not implemented it. Read your code again and try to find the piece where you actually compare two Item instances. There's is none.
You should implement an Equals and GetHashCode method on your Item class, something like this:
public override bool Equals(Object obj)
{
var o = (Item)obj;
// Note: not error checking :-)
return SortPropA.Equals(o.SortPropA) ||
SortPropB.Equals(o.SortPropB) ||
SortPropC.Equals(o.SortPropC) ||
SortPropD.Equals(o.SortPropD) ||
SortPropE.Equals(o.SortPropE);
}
or create a class that implements IEqualityComparer<Item> that handles this requirement.

Using Linq Correct Quiz and Group by Topic

I have 3 lists and classes:
List<student_Answers> student_answer = new List<student_Answers>
{new student_Answers {id = "1", q1 ="*C", q2= "*D", q3 = "*B", q4= "*A" },
new student_Answers {id = "2", q1 ="*D", q2= "*E", q3 = "*B", q4= "*A" }};
List<answer> correct_answer = new List<answer>
{new answer{r1 ="*C", r2= "*D", r3 = "*B", r4= "*C" }};
List<Topic> topic_question = new List<Topic>
{ new Topic{ q1_topic ="Verb to be", q2_topic= "Verb to be", q3_topic = "Listening", q4_topic= "Listening" }};
I tried:
foreach (var na in student_answer)
{var grade = from n in student_answer where !na.Contains(n) select n;}
It doesn't work and I don't know how group my questions in topics.
Expected Output :
Failed question:
Id= 1 : Failed in question = 4 : Topic = "Listening"
Id= 2 : Failed in question = 1 : Topic = "Verb to be"
Id= 2 : Failed in question = 4 : Topic = "Listening"
Topic percent:
Listening = 2/4 = 50% incorrect
Verb to be = 1/4 = 25% incorrect

Here's some code to point you in the right direction.
public class StudentQuestion : List<Question>
{
public int StudentId { get; set; }
public StudentQuestion(int studentId, IEnumerable<Question> questions)
:base(questions)
{
StudentId = studentId;
}
public bool AddAnswer(int id, string response)
{
Question question = null;
if((question = this.SingleOrDefault(q => q.Id == id)) == null)
return false;
question.Answer = response;
return true;
}
public bool RemoveAnswer(int id)
{
Question question = null;
if((question = this.SingleOrDefault(q => q.Id == id)) == null)
return false;
question.Answer = string.Empty;
return true;
}
public double ScoreTest(IEnumerable<Answer> answers)
{
List<bool> score = this.Join(answers, a1 => a1.Answer.Response, a2 => a2.Response, (a1, a2) => a1.HasCorrectAnswer(a2)).ToList();
return ((double)score.Where(s => s).Count()) / score.Count;
}
}
public class Question
{
public int Id { get; set; }
public string Text { get; set; }
public Answer Answer { get; set; }
public bool HasCorrectAnswer(Answer correctAnswer)
{
return correctAnswer == Answer;
}
}
public class Answer : IEquatable<Answer>
{
public string Response { get; set; }
public bool Equals(Answer answer)
{
if(answer == null) return false;
return string.Compare(this.Response, answer.Response, true) == 0;
}
public override bool Equals(object obj)
{
if(obj == null)
return false;
var answerObj = obj as Answer;
return answerObj == null ? false : Equals(answerObj);
}
public override int GetHashCode()
{
return Response.GetHashCode();
}
public static bool operator == (Answer answer1, Answer answer2)
{
if ((object)answer1 == null || ((object)answer2) == null)
return object.Equals(answer1, answer2);
return answer1.Equals(answer2);
}
public static bool operator != (Answer answer1, Answer answer2)
{
if ((object)answer1 == null || ((object)answer2) == null)
return ! object.Equals(answer1, answer2);
return ! (answer1.Equals(answer2));
}
}

LINQ Query Fails to identify duplicates

I have two custom classes.
The first class contains basic data:
public class Request
{
public Request(int lineID, string partNo, int qty, int reasonID, int typeID)
{
LineID = lineID;
PartNo = partNo;
Qty = qty;
ReasonID = reasonID;
TypeID = typeID;
}
public int LineID { get; private set; }
public string PartNo { get; private set; }
public int Qty { get; internal set; }
public int ReasonID { get; private set; }
public int TypeID { get; private set; }
}
The second class contains a List of these Request objects, with a signature as follows:
public class Requests : IEnumerable<Request>
{
private List<Request> list;
public Requests()
{
list = new List<Request>();
}
public int Add(Request item)
{
if (item != null)
{
foreach (var x in list.Where(r =>
(r.LineID == item.LineID) &&
(r.PartNo == item.PartNo) &&
(r.ReasonID == item.ReasonID) &&
(r.TypeID == item.TypeID)))
{
x.Qty += item.Qty;
return list.IndexOf(x);
}
list.Add(item);
return list.Count - 1;
}
return -1;
}
// other code
}
I am testing my code and adding items is putting new items into the list, but the LINQ query to find duplicates is not working.
If 2 identical items are added to the list, I want my code to be smart enough to simply update the quantity, but it does not seem to be working.
Could someone tell me what is wrong with the LINQ query?

Could someone tell me what is wrong with the LINQ query?
Theoretically it looks OK. I think we need to know more information about your data to be able to find out why it isn't working as you expect. Does the combination of LineID, PartNo, ReasonID, and TypeID uniquely distinguish an item? Since PartNo is a string, are the values case-insensitive (your comparison is case-sensitive)?
If 2 identical items are added to the list, I want my code to be smart enough to simply update the quantity, but it does not seem to be working.
For this I would suggest a different approach. Consider overriding Equals() on your Request type. Then your Add method can just check if the list already contains the item, incrementing the quantity if so and adding it if not:
var idx = list.IndexOf(item);
if(idx != -1)
{
list[idx].Qty += item.Qty;
}
else
{
list.Add(item);
}

Make Request implement IEquatable<Request>, because this is what IndexOf uses:
public bool Equals(Request other) {
return other != null && (this.LineID == other.LineID) && (this.PartNo == other.PartNo) && (this.ReasonID == other.ReasonID) && (this.TypeID == other.TypeID);
}
Then:
public int Add(Request item) {
if (item != null)
{
int ind = list.IndexOf(item);
if (ind == -1)
{
list.Add(item);
return list.Count - 1;
}
else
{
list[ind].Qty += item.Qty;
return ind;
}
}
return -1;
}

You can modify the method by materializing LINQ query. For example:
public int Add(Request item) {
if (item != null) {
foreach (var x in list.Where(r =>
(r.LineID == item.LineID) &&
(r.PartNo == item.PartNo) &&
(r.ReasonID == item.ReasonID) &&
(r.TypeID == item.TypeID)
).ToList()) {
x.Qty += item.Qty;
return list.IndexOf(x);
}
list.Add(item);
return list.Count - 1;
}
return -1;
}
But, because your Requests must be unique, you can use this
public int Add(Request item)
{
if (item != null)
{
var req = list.SingleOrDefault(r =>
(r.LineID == item.LineID) &&
(r.PartNo == item.PartNo) &&
(r.ReasonID == item.ReasonID) &&
(r.TypeID == item.TypeID)
);
if(req!=null)
{
req.Qty += item.Qty;
return list.IndexOf(req);
}
list.Add(item);
return list.Count - 1;
}
return -1;
}