Question

I have a requirement to retrieve an item from a data structure by key. But I also have a requirement to traverse that data structure in sorted order, using a field other than the key.

Something like this (pseudocode, for illustrative purposes only):

var list = new SortedDictionary<TKey, TSortField, TItem>();

How would I do this? Is there a way to use a single data structure, or do I need to roll my own?

NOTE: TItem already derives from (and implements)IComparable<T>.

Answer 1

If you’re not going to be modifying the result of the sort, you could use a combination of IEnumerable.OrderBy and ToDictionary:

var sortedResult = sortedDictionary.OrderBy(kvp => kvp.Value.SortField)
                                   .ToDictionary(kvp => kvp.Key,
                                                 kvp => kvp.Value);

Just keep in mind that this is really creating a new collection rather than sorting the original (which will be maintained in the SortedDictionary).