CODEWITHSUNDEEP
c#listcomparison
user1187135
user1187135

Reputation:

How to use SequenceEqual to compare coordinates?

If the nested int[] contains coordinates x, y, how do I compare them using SequenceEqual?

The List are a group of coordinates. I want to check every other List to see if they have the same number of coordinates and also the same coordinate values. If they both match, I want to remove the redundant one. Otherwise, leave it. 

  private List<List<int[]>> combineList(List<List<int[]>> matches){
        Debug.Log (matches.Count());

        foreach(List<int[]> tileGroup in matches){
            foreach(List<int[]> other in matches){
                if(other == tileGroup) continue;

                if(sequenceEqual(tileGroup, other)){
                    matches.Remove(other);
                }   


            }
        }

        Debug.Log (matches.Count());

        return matches;
    }

    private bool sequenceEqual(List<int[]> groupA, List<int[]> groupB){
        if(groupA.Count() == groupB.Count()){
            int i = 0, j = 0;
            Dictionary<int, int[]>  dictA = new Dictionary<int, int[]>(), 
                                    dictB = new Dictionary<int, int[]>();   

            foreach(int[] coordinate in groupA){
                dictA.Add (i, coordinate);
                i++;
            }

            foreach(int[] coordinate in groupB){
                dictB.Add (j, coordinate);  
                j++;
            }

            return dictA.Values.SequenceEqual(dictB.Values);
        } 

        return false;
    }

Upvotes: 0

Views: 283

Answers (1)

Jesse Sweetland
Jesse Sweetland

Reputation: 1614

Probably the quickest way would be to implement an IEqualityComparer<int[]>:

class IntArrayEqualityComparer : IEqualityComparer<int[]>
{
    public bool Equals(int[] x, int[] y)
    {
        if (ReferenceEquals(x, y)) return true;
        if (ReferenceEquals(null, x)) return false;
        if (ReferenceEquals(null, y)) return false;
        if (x.Length != y.Length) return false;
        for (var i = 0; i < x.Length; i++)
        {
            if (x[i] != y[i]) return false;
        }
        return true;
    }

    public int GetHashCode(int[] x)
    {
        if (x == null) return 0;
        var hashCode = 0;
        for (var i = 0; i < x.Length; i++)
        {
            hashCode = (32 * hashCode) + x[i];
        }
        return hashCode;
    }
}

And then use the overloaded version of IEnumerable<TSource>.SequenceEqual:

private bool sequenceEqual(List<int[]> groupA, List<int[]> groupB)
{
    if (ReferenceEquals(groupA, groupB)) return true;
    if (ReferenceEquals(null, groupA)) return false;
    if (ReferenceEquals(null, groupB)) return false;
    return groupA.SequenceEqual(groupB, new IntArrayEqualityComparer());
}

In the long run it might be beneficial to create a Coordinates type that simply implements IEquatable<Coordinates>, in which case you would simply be comparing two List<Coordinates> objects.

Upvotes: 1

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