CODEWITHSUNDEEP
c#listlinq
stackMeUp
stackMeUp

Reputation: 552

Comparing a list of values against the property of an object (list) using LINQ

I am having trouble comparing two lists using Linq.
My first list contains object instances, which contain a property of interest, to be compared against a second list that contains only values.
Say we have:

List<uint> referenceValues = new List<uint>(){1, 2, 3};
and
List<SomeObject> myObject= new List<SomeObject>();

Now the SomeObject() class has the property "Value" of type uint.
Note that "myObject" list may contains more elements than the "referenceValues" list and we therefore have to select the appropriate portion of "myObject" to be compared against "referenceValues".

I have found the following stack overflow question, which is related, but not quite what I am after: link

Here is what I have tried so far, but without success:

if (myObject
    .GetRange((int)offset, count)       // Extracted the object of interest from the list
    .Where(x => referenceValues.Equals(x.Value)).Count() == 0)   // Comparing the "Value" properties against the "referenceValues"
{
    // Do something
}

I think I need to use "SequenceEqual" somehow, but I am not really getting how to.
Any advice would be very welcome.

EDIT

Reproducible example:

using System;
using System.Linq;
using System.Collections.Generic;
                    
public class Program
{
    public static void Main()
    {
        int offset = 0;
            
        List<uint> referenceValues = new List<uint>(){1, 2, 3};

        List<SomeObject> myObject= new List<SomeObject>(){new SomeObject(){Value=1}, 
                                                          new SomeObject(){Value=2},
                                                          new SomeObject(){Value=3}};
        
        if (myObject
            .GetRange(offset, referenceValues.Count()-1)       // Extracted the object of interest from the list
            .Where(x => referenceValues.Equals(x.Value)).Count() == referenceValues.Count())   // Comparing the "Value" properties against the "referenceValues"
        {
            // Do something
            Console.WriteLine("Lists are matching!");
        }
        else
        {
            Console.WriteLine("Lists are not matching!");
        }
    }
}

public class SomeObject
{
    public uint Value = 0;
}

EDIT2

Working solution as per suggestion from Guru Stron:

using System;
using System.Linq;
using System.Collections.Generic;
                    
public class Program
{
    public static void Main()
    {
        int offset = 0;
            
        List<uint> referenceValues = new List<uint>(){1, 2, 3};

        List<SomeObject> myObject= new List<SomeObject>(){new SomeObject(){Value=1}, 
                                                          new SomeObject(){Value=2},
                                                          new SomeObject(){Value=3}};
        
        if (myObject.
            GetRange((int)offset, referenceValues.Count())   
            .Select(someObject => someObject.Value)
            .SequenceEqual(referenceValues))
        {
            // Do something
            Console.WriteLine("Lists are matching!");
        }
        else
        {
            Console.WriteLine("Lists are not matching!");
        }
    }
}

public class SomeObject
{
    public uint Value = 0;
}

Recommended book about Linq expressions: LINQ Pocket Reference

Upvotes: 0

Views: 102

Answers (2)

Guru Stron
Guru Stron

Reputation: 141600

If you want to check if some subset of myObject values has some concrete order by some property you can do something like this:

bool inOrder = myObject
    .GetRange((int)offset, count)   
    .Select(someObject => someObject.Value)
    .SequenceEqual(referenceValues);

If you want to just check that all values are present in the specified referenceValues you can use All (also if source range is empty this returns true):

bool allPresent = myObject
    .GetRange((int)offset, count)   
    .All(someObject => referenceValues.Contains(someObject.Value));

For full collection match without ordering I don't know out of box solution but you can look for one for example here.

Upvotes: 1

Ralf
Ralf

Reputation: 1352

if(myObject.Any(x => referenceValues.Contains(x.Value)) {}

I ignored the GetRange part but should make no difference.

Upvotes: 0

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