Comparing two lists to find the difference

Question

So I am shooting coloured darts at a spinning board. When the dart hits the board it will perform a check using Physics2D.OverlapCircleAll for any nearby darts which are of the same colour. If there are any detected it will add them to a list called Links. I want to be able to compare the other dart's Link list with the current dart and if there is any differences to be able to add that to the current list.

 ![public class DartOptimized : MonoBehaviour
 {
 
     // Speed of the Dart
     public float Velocity;
 
     // Board transform
     Transform boardTransform;
     // This dart transform
     Transform thisDartTransform;
     //This dart layer
     LayerMask thisLayer;
 
     // Stopping distance for dart
     public float boardContact;
 
     // Distance to check for surrounding darts once contact is made with the board
     public float checkRadius;
 
     // Links list
     public List<GameObject> Links = new List<GameObject>();
     // Material for line 
     public Material LineRenderMat;
 
 
     // Game Manager Script for score
     GameManagerScript GM;
 
 
     public Collider2D[] checkForSurroundingDarts;
 
 
     private void Start()
     {
         boardTransform = GameObject.FindGameObjectWithTag("Board").transform;
         thisDartTransform = gameObject.transform;
         thisLayer = gameObject.layer;
 
         GM = GameObject.FindObjectOfType<GameManagerScript>();
     }
 
 
     private void Update()
     {
         if (gameObject.tag == "Dart")
         {
 
             // Distance between the board and this dart
             float distance = Vector3.Distance(boardTransform.position, thisDartTransform.position);
             if (distance > boardContact)
             {
                 // Move Dart
                 transform.Translate(new Vector3(0f, Velocity * Time.deltaTime, 0f));
             }
             else
             {
                 gameObject.tag = "Pinned";
                 Invoke("AttachDartToBoard", 0);
             }
         }
     }
 
     private void AttachDartToBoard()
     {
         this.gameObject.transform.SetParent(boardTransform);
         GM.scoreValue++;
 
         checkForSurroundingDarts = Physics2D.OverlapCircleAll(transform.position, checkRadius);
         for (var i = 0; i < checkForSurroundingDarts.Length; i++)
         {
             if (checkForSurroundingDarts[i].gameObject.tag == "Pinned" && checkForSurroundingDarts[i].gameObject.layer == this.gameObject.layer)
             {
                 if (checkForSurroundingDarts[i].gameObject.GetComponent<DartOptimized>().Links.Count <= 1)
                 {
                     Links.Add(checkForSurroundingDarts[i].gameObject);
                 }
                 else if (checkForSurroundingDarts[i].gameObject.GetComponent<DartOptimized>().Links.Count > 1)
                 {
                     Links.Add(checkForSurroundingDarts[i].gameObject);
 
                     
                     //Links.AddRange(checkForSurroundingDarts[i].gameObject.GetComponent<DartOptimized>().Links);
                 }
             }
         }
     }][1]

[1]: /storage/temp/118843-links.png

Answer 1

Best Answer

Answer by bakir-omarov · Jun 13, 2018 at 02:15 PM

List have a function Contains, it will check if Object is in list or not.

 public class MyCode: MonoBehaviour
 {
 
     private List<GameObject> m_myList;
     private GameObject m_myGameObject;
 
 
     void Check()
     {
         if (ListContains(m_myList, m_myGameObject))
             Debug.Log("It already has this Gameobjet");
         else
             Debug.Log("We don't have this GameObject in this list");
     }
 
     private bool ListContains(List<GameObject> _list,GameObject _gameObj)
     {
         if (_list.Contains(_gameObj))     
             return true;
         else
             return false;
     }
 }

UPDATED:
So if you want to compare listOne and listTwo, and add all elements that is not in List Two, just use:

     void Check(List<GameObject> _listOne, List<GameObject> _listTwo)
     {
         foreach (GameObject _GO in _listOne)
         {
             if (!_listTwo.Contains(_GO))
                 _listTwo.Add(_GO);
         }
     }

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Dorinbuzilov · Jun 13, 2018 at 02:43 PM 1

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Thanks for the response, I was told that using foreach isn't so good because it will create garbage that will slow down the application later?

WinterboltGames Dorinbuzilov · Jun 13, 2018 at 02:59 PM 0

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it's very un-noticeable if you didn't do it too much and never ever make a for-each loop in Update, FixedUpdate or LateUpdate

Dorinbuzilov WinterboltGames · Jun 13, 2018 at 04:27 PM 0

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Is it still ok to do this if the second list im trying to compare to is part of another instance.

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Comparing two lists to find the difference

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