SoftCircuits / OrderedDictionary

.NET library that implements an ordered dictionary.

OrderedDictionary

Install-Package SoftCircuits.OrderedDictionary

Introduction

OrderedDictionary is a .NET library that implements an ordered dictionary. It provides all the functionality of Dictionary<TKey, TValue> but also maintains the items in an ordered list. Items can be added, removed and accessed by key or index. For compatibility, the class implements the IDictionary and IReadOnlyDictionary interfaces.

Examples

OrderedDictionary can be initialized used like any other dictionary. This includes initializing with index initializers.

OrderedDictionary<int, string> dictionary = new()
{
    [101] = "Bob Smith",
    [127] = "Gary Wilson",
    [134] = "Ann Carpenter",
    [187] = "Bill Jackson",
    [214] = "Cheryl Hansen",
};

Like a dictionary, items can by accessed by key. They can also be accessed using a 0-based index. Because it's possible for the key to be of type int, the ByIndex property is used to access an item using an index. This prevents any ambiguity between key and index values.

Assert.AreEqual("Gary Wilson", dictionary[127]);
Assert.AreEqual("Bill Jackson", dictionary.ByIndex[3]);

You can add items using the Add() method, and you can also insert them at a particular location.

OrderedDictionary<int, string> dictionary = new();

dictionary.Add(101, "Bob Smith");
dictionary.Add(127, "Gary Wilson");
dictionary.Add(187, "Bill Jackson");
dictionary.Add(214, "Cheryl Hansen");

dictionary.Insert(2, 134, "Ann Carpenter");

Assert.AreEqual("Bob Smith", dictionary[101]);
Assert.AreEqual("Bob Smith", dictionary.ByIndex[0]);
Assert.AreEqual("Gary Wilson", dictionary[127]);
Assert.AreEqual("Gary Wilson", dictionary.ByIndex[1]);
Assert.AreEqual("Ann Carpenter", dictionary[134]);
Assert.AreEqual("Ann Carpenter", dictionary.ByIndex[2]);
Assert.AreEqual("Bill Jackson", dictionary[187]);
Assert.AreEqual("Bill Jackson", dictionary.ByIndex[3]);
Assert.AreEqual("Cheryl Hansen", dictionary[214]);
Assert.AreEqual("Cheryl Hansen", dictionary.ByIndex[4]);

Items can also be removed using either the key or index.

OrderedDictionary<int, string> dictionary = new()
{
    [101] = "Bob Smith",
    [127] = "Gary Wilson",
    [134] = "Ann Carpenter",
    [187] = "Bill Jackson",
    [214] = "Cheryl Hansen",
};

dictionary.Remove(134); // Removes 134 - Add Carpenter
dictionary.RemoveAt(2); // Removes 187 - Bill Jackson

Assert.AreEqual(5 - 2, dictionary.Count);
Assert.IsTrue(dictionary.ContainsKey(101));
Assert.IsTrue(dictionary.ContainsKey(127));
Assert.IsFalse(dictionary.ContainsKey(134));
Assert.IsFalse(dictionary.ContainsKey(187));
Assert.IsTrue(dictionary.ContainsKey(214));

You can also iterate through an OrderedDictionary using foreach.

foreach (KeyValuePair<int, string> item in dictionary)
{
    Console.WriteLine(item.Key);
    Console.WriteLine(item.Value);
}

To iterate the keys or values only, you can use the Keys or Values properies.

The library also defines the ToOrderedDictionary() extension method with several overloads for converting IEnumerable<>s to OrderedDictionary<>s.