Sorting list based on sorted point list - Error

frodriguezmXYFSS · February 25, 2021, 1:12pm

Dear,

I’m trying to sort a list based on a list points. I’m using the “list.SortByKey” node, being the point list the keys, but it’s not working. Additionally, I can sort the list point with “List.Sort” node without any problem.

Find pics below to explain the issue.

Daan · February 25, 2021, 1:49pm

How do you want to sort your points list? You could try the nodes list.indexof and list.getitematindex after your List.Sort node. (if the List.SortByKey node doesnt work with a list of points as keys)

frodriguezmXYFSS · February 25, 2021, 2:31pm

I don’t really care the “How I want to sort”, I’m caring on why it’s working with “List.Sort” node and it’s not such as key on “List.SortByKey” node

Michael_Kirschner2 · February 25, 2021, 4:50pm

points are not intrinsically comparable - List.Sort tries to sort the input list in a few different ways, likely it just settles on using the hashcode (see last line), which might kind of work, if the hashcode is based on the fields of the point, you might get exact duplicates near next to each other - but it’s not precise enough to be valuable unless you know all the details.

github.com

DynamoDS/Dynamo/blob/2a74892bd161a7592f15a68a1ce3e125b49c571e/src/Libraries/CoreNodes/List.cs#L1998


///     Implements Compare function for two objects using following rule.
///     1. Numbers are assumed to be smallest, then bool, string and pointers.
///     2. If the two objects are IComparable and of the same type, then use
///     it's native comparison mechanism.
///     3. If both inputs are value type, but one of them is bool, bool is bigger
///     4. Otherwise Convert them all to double and compare.
///     5. Else If only one is value type, then value type object is smaller
///     6. Else If only one is string, then the string is smaller than other
///     7. Else don't know how to compare, so best campare them based on HashCode.
/// </summary>
internal class ObjectComparer : IComparer<object>
{
    public int Compare(object x, object y)
    {
        Type xType = x.GetType();
        Type yType = y.GetType();

        //Same type and are comparable, use it's own compareTo method.
        if (xType == yType && typeof(IComparable).IsAssignableFrom(xType))
            return ((IComparable)x).CompareTo(y);

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Sorting list based on sorted point list - Error

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