CODEWITHSUNDEEP
c#arrayssorting
spainchaud
spainchaud

Reputation: 411

Sorting array by item type

I have an array of objects that I sort by type. Within that array is a set of objects of one type that are already in their preferred relative order. After the sort, these objects are grouped together, but no longer in the same order. I am using the sort a follows

Array.Sort(shapes, GetVisualComparer());

I have looked for a sort method that promises to preserve original order, but have found nothing.

I will note that I have a workaround, but it adds unnecessary confusion to the code, and does not address the general problem if it comes up in the future.

Upvotes: 2

Views: 290

Answers (2)

Jan Dörrenhaus
Jan Dörrenhaus

Reputation: 6717

Make a copy of the original array. Then, make your comparer compare the original indexes of your elements if their type is equal.

I don't know on what you base your type sorting, but sorting by name, it would look somewhat like this:

public class TypeComparer : IComparer<Type>
{
    public int Compare(Type x, Type y)
    {
        int result = StringComparer.InvariantCulture.Compare(x.Name, y.Name);
        if (result == 0)
        {
            result = Array.IndexOf(originalArray, x).CompareTo(Array.IndexOf(originalArray, y));
        }
        return result;
    }
}

Upvotes: 2

alc
alc

Reputation: 1557

The problem is that Array.Sort<T>(T[], IComparer<T>) is not using a stable sort.

This implementation performs an unstable sort; that is, if two elements are equal, their order might not be preserved. In contrast, a stable sort preserves the order of elements that are equal.

You'll have to sort your array using some other method.

Upvotes: 2

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