multimap in .NET

Ho bisogno di un equivalente di std::multimap di c ++ in C-sharp. Esiste nella libreria standard?

Perché è quasi Natale 🙂

 ////////////////////////////////////////////////////////////////////// // Algorithmia is (c) 2008 Solutions Design. All rights reserved. // http://www.sd.nl ////////////////////////////////////////////////////////////////////// // COPYRIGHTS: // Copyright (c) 2008 Solutions Design. All rights reserved. // // The Algorithmia library sourcecode and its accompanying tools, tests and support code // are released under the following license: (BSD2) // ---------------------------------------------------------------------- // Redistribution and use in source and binary forms, with or without modification, // are permitted provided that the following conditions are met: // // 1) Redistributions of source code must retain the above copyright notice, this list of // conditions and the following disclaimer. // 2) Redistributions in binary form must reproduce the above copyright notice, this list of // conditions and the following disclaimer in the documentation and/or other materials // provided with the distribution. // // THIS SOFTWARE IS PROVIDED BY SOLUTIONS DESIGN ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, // INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A // PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL SOLUTIONS DESIGN OR CONTRIBUTORS BE LIABLE FOR // ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT // NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR // BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, // STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE // USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. // // The views and conclusions contained in the software and documentation are those of the authors // and should not be interpreted as representing official policies, either expressed or implied, // of Solutions Design. // ////////////////////////////////////////////////////////////////////// // Contributers to the code: // - Frans Bouma [FB] ////////////////////////////////////////////////////////////////////// using System; using System.Collections.Generic; using System.Linq; using System.Text; using SD.Tools.Algorithmia.UtilityClasses; namespace SD.Tools.Algorithmia.GeneralDataStructures { ///  /// Extension to the normal Dictionary. This class can store more than one value for every key. It keeps a HashSet for every Key value. /// Calling Add with the same Key and multiple values will store each value under the same Key in the Dictionary. Obtaining the values /// for a Key will return the HashSet with the Values of the Key. ///  /// The type of the key. /// The type of the value. public class MultiValueDictionary : Dictionary> { ///  /// Initializes a new instance of the  class. ///  public MultiValueDictionary() : base() { } ///  /// Adds the specified value under the specified key ///  /// The key. /// The value. public void Add(TKey key, TValue value) { ArgumentVerifier.CantBeNull(key, "key"); HashSet container = null; if(!this.TryGetValue(key, out container)) { container = new HashSet(); base.Add(key, container); } container.Add(value); } ///  /// Determines whether this dictionary contains the specified value for the specified key ///  /// The key. /// The value. /// true if the value is stored for the specified key in this dictionary, false otherwise public bool ContainsValue(TKey key, TValue value) { ArgumentVerifier.CantBeNull(key, "key"); bool toReturn = false; HashSet values = null; if(this.TryGetValue(key, out values)) { toReturn = values.Contains(value); } return toReturn; } ///  /// Removes the specified value for the specified key. It will leave the key in the dictionary. ///  /// The key. /// The value. public void Remove(TKey key, TValue value) { ArgumentVerifier.CantBeNull(key, "key"); HashSet container = null; if(this.TryGetValue(key, out container)) { container.Remove(value); if(container.Count <= 0) { this.Remove(key); } } } ///  /// Merges the specified multivaluedictionary into this instance. ///  /// To merge with. public void Merge(MultiValueDictionary toMergeWith) { if(toMergeWith==null) { return; } foreach(KeyValuePair> pair in toMergeWith) { foreach(TValue value in pair.Value) { this.Add(pair.Key, value); } } } ///  /// Gets the values for the key specified. This method is useful if you want to avoid an exception for key value retrieval and you can't use TryGetValue /// (eg in lambdas) ///  /// The key. /// if set to true and the key isn't found, an empty hashset is returned, otherwise, if the key isn't found, null is returned ///  /// This method will return null (or an empty set if returnEmptySet is true) if the key wasn't found, or /// the values if key was found. ///  public HashSet GetValues(TKey key, bool returnEmptySet) { HashSet toReturn = null; if(!base.TryGetValue(key, out toReturn) && returnEmptySet) { toReturn = new HashSet(); } return toReturn; } } } 

ILookup potrebbe essere abbastanza buono per te – ma sfortunatamente non ci sono implementazioni pubbliche. Devi fondamentalmente passare attraverso Enumerable.ToLookup , per quanto ne so. Ciò significa che è una sorta di “build una volta” di mappa: non puoi aggiungerla in seguito. Tuttavia, se è tutto ciò di cui hai bisogno è comodo poter usare solo le cose integrate.

In .NET 3.5, c’è un ILookup<,> che rappresenta questo. L’implementazione regolare ( Lookup<,> ) è immutabile, ma ho un EditableLookup<,> in MiscUtil che dovrebbe fare bene il lavoro.

puoi provarlo

C # MultiMap Classe generica

http://dotnetperls.com/multimap

Implementazione multimap molto semplice.

puoi trovare ac # multimap collection @ http://code.google.com/p/self-balancing-avl-tree/ . è basato su un albero av bilanciante che è anche incluso nel codice.

Considera l’utilizzo di BMultiMap se la tua raccolta nel suo complesso è grande. Salva molta memoria rispetto al Dictionary> , specialmente se il numero di valori associati a ciascun tasto è spesso piccolo.