Filtering out values from a C# Generic Dictionary

Question

I have a C# dictionary, Dictionary that I need to be filtered based on a property of MyObject.

For example, I want to

Answer 1

I added the following extension method for my project which allows you to filter an IDictionary.

public static IDictionary KeepWhen(
    this IDictionary dict,
    Predicate predicate
) {
    return dict.Aggregate(
        new Dictionary(),
        (result, keyValPair) =>
        {
            var key = keyValPair.Key;
            var val = keyValPair.Value;

            if (predicate(val))
                result.Add(key, val);

            return result;
        }
    );
}

Usage:

IDictionary oldPeople = personIdToPerson.KeepWhen(p => p.age > 29);