utilisation propre IComparer <T> avec Linq OrderBy

Question

J'ai un

List<MyClass> 

générique où MyClass possède une propriété InvoiceNumber qui contient des valeurs telles que:

200906/1
200906/2
..
200906/10
200906/11
200906/12

Ma liste est liée à un

BindingList<T> 

qui prend en charge le tri avec LINQ:

protected override void ApplySortCore(
      PropertyDescriptor property, ListSortDirection direction) 
{ 

    _sortProperty = property; 
    _sortDirection = direction; 

    var items = this.Items; 

    switch (direction) 
    { 
     case ListSortDirection.Ascending: 
      items = items.OrderByDescending(x => property.GetValue(x)).ToList(); 
      break; 
     case ListSortDirection.Descending: 
      items = items.OrderByDescending(x => property.GetValue(x)).ToList(); 
      break; 
    } 

    this.Items = items; 

} 

Cependant, les types de comparateur par défaut (comme on le suppose) comme celui-ci:

200906/1
200906/10
200906/11
200906/1 2
200906/2

qui est méchant dans ce cas. Je veux maintenant utiliser mon propre IComparer<T> avec ceci. Il ressemble à ceci:

public class MyComparer : IComparer<Object> 
{ 

    public int Compare(Object stringA, Object stringB) 
    { 
     String[] valueA = stringA.ToString().Split('/'); 
     String[] valueB = stringB.ToString().Split('/'); 

     if(valueA .Length != 2 || valueB .Length != 2) 
      return String.Compare(stringA.ToString(), stringB.ToString()); 

     if (valueA[0] == valueB[0]) 
     { 
      return String.Compare(valueA[1], valueB[1]); 
     } 
     else 
     { 
      return String.Compare(valueA[0], valueB[0]); 
     } 

    } 

} 

et a changé le code ApplySortCore utiliser cette IComparer:

case ListSortDirection.Ascending: 
    MyComparer comparer = new MyComparer(); 
    items = items.OrderByDescending(
       x => property.GetValue(x), comparer).ToList(); 
    break; 

Quand je déboguer mon code, je vois que MyComparer.Compare(object, object) est appelé plusieurs fois et renvoie les bonnes valeurs (- 1, 0, 1) pour une méthode de comparaison.

Mais ma liste est toujours triée de la "mauvaise" manière. Est-ce que je manque quelque chose? Je n'ai aucune idée.

Answer 1

Votre comparateur a tort pour moi. Vous êtes toujours en train de trier par ordre de texte par défaut. Certes, vous voulez être l'analyse syntaxique des deux nombres et le tri en fonction de ce qui suit:

public int Compare(Object stringA, Object stringB) 
{ 
    string[] valueA = stringA.ToString().Split('/'); 
    string[] valueB = stringB.ToString().Split('/'); 

    if (valueA.Length != 2 || valueB.Length != 2) 
    { 
     stringA.ToString().CompareTo(stringB.ToString())); 
    } 

    // Note: do error checking and consider i18n issues too :) 
    if (valueA[0] == valueB[0]) 
    { 
     return int.Parse(valueA[1]).CompareTo(int.Parse(valueB[1])); 
    } 
    else 
    { 
     return int.Parse(valueA[0]).CompareTo(int.Parse(valueB[0])); 
    } 
} 

(Notez que cela ne cadre pas très bien avec votre question indiquant que vous avez débogués à travers et vérifié que Compare est la bonne valeur de retour - mais je crains que je soupçonne une erreur humaine sur ce front.)

De plus, Sven a le droit de changer la valeur de items et de ne pas modifier votre liste de liens. Vous devez ajouter:

this.Items = items; 

au bas de votre méthode.

Answer 2

La liste triée est uniquement liée aux éléments de variable locale, pas à la propriété Items de votre liste de liaison, par conséquent, elle reste non triée.

[Modifier] Fondamentalement, vous êtes tout simplement jeter le résultat de vos efforts de tri ;-)

Answer 3

je rencontrais la question du tri naturel général et blogué la solution ici:

Natural Sort Compare with Linq OrderBy()

public class NaturalSortComparer<T> : IComparer<string>, IDisposable 
{ 
    private bool isAscending; 

    public NaturalSortComparer(bool inAscendingOrder = true) 
    { 
     this.isAscending = inAscendingOrder; 
    } 

    #region IComparer<string> Members 

    public int Compare(string x, string y) 
    { 
     throw new NotImplementedException(); 
    } 

    #endregion 

    #region IComparer<string> Members 

    int IComparer<string>.Compare(string x, string y) 
    { 
     if (x == y) 
      return 0; 

     string[] x1, y1; 

     if (!table.TryGetValue(x, out x1)) 
     { 
      x1 = Regex.Split(x.Replace(" ", ""), "([0-9]+)"); 
      table.Add(x, x1); 
     } 

     if (!table.TryGetValue(y, out y1)) 
     { 
      y1 = Regex.Split(y.Replace(" ", ""), "([0-9]+)"); 
      table.Add(y, y1); 
     } 

     int returnVal; 

     for (int i = 0; i < x1.Length && i < y1.Length; i++) 
     { 
      if (x1[i] != y1[i]) 
      { 
       returnVal = PartCompare(x1[i], y1[i]); 
       return isAscending ? returnVal : -returnVal; 
      } 
     } 

     if (y1.Length > x1.Length) 
     { 
      returnVal = 1; 
     } 
     else if (x1.Length > y1.Length) 
     { 
      returnVal = -1; 
     } 
     else 
     { 
      returnVal = 0; 
     } 

     return isAscending ? returnVal : -returnVal; 
    } 

    private static int PartCompare(string left, string right) 
    { 
     int x, y; 
     if (!int.TryParse(left, out x)) 
      return left.CompareTo(right); 

     if (!int.TryParse(right, out y)) 
      return left.CompareTo(right); 

     return x.CompareTo(y); 
    } 

    #endregion 

    private Dictionary<string, string[]> table = new Dictionary<string, string[]>(); 

    public void Dispose() 
    { 
     table.Clear(); 
     table = null; 
    } 
} 

Answer 4

Vous pouvez utiliser l'algorithme Alphanum:

(...) 
    items.OrderBy(x => property.GetValue(x), new AlphanumComparator()) 
    (...) 

AlphanumComparator

/* 
* The Alphanum Algorithm is an improved sorting algorithm for strings 
* containing numbers. Instead of sorting numbers in ASCII order like 
* a standard sort, this algorithm sorts numbers in numeric order. 
* 
* The Alphanum Algorithm is discussed at http://www.DaveKoelle.com 
* 
* Based on the Java implementation of Dave Koelle's Alphanum algorithm. 
* Contributed by Jonathan Ruckwood <jonathan.ruckwood@gmail.com> 
* 
* Adapted by Dominik Hurnaus <dominik.hurnaus@gmail.com> to 
* - correctly sort words where one word starts with another word 
* - have slightly better performance 
* 
* Released under the MIT License - https://opensource.org/licenses/MIT 
* 
* Permission is hereby granted, free of charge, to any person obtaining 
* a copy of this software and associated documentation files (the "Software"), 
* to deal in the Software without restriction, including without limitation 
* the rights to use, copy, modify, merge, publish, distribute, sublicense, 
* and/or sell copies of the Software, and to permit persons to whom the 
* Software is furnished to do so, subject to the following conditions: 
* 
* The above copyright notice and this permission notice shall be included 
* in all copies or substantial portions of the Software. 
* 
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. 
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, 
* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR 
* OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE 
* USE OR OTHER DEALINGS IN THE SOFTWARE. 
* 
*/ 
using System; 
using System.Collections; 
using System.Text; 

/* 
* Please compare against the latest Java version at http://www.DaveKoelle.com 
* to see the most recent modifications 
*/ 
namespace AlphanumComparator 
{ 
    public class AlphanumComparator : IComparer 
    { 
     private enum ChunkType {Alphanumeric, Numeric}; 
     private bool InChunk(char ch, char otherCh) 
     { 
      ChunkType type = ChunkType.Alphanumeric; 

      if (char.IsDigit(otherCh)) 
      { 
       type = ChunkType.Numeric; 
      } 

      if ((type == ChunkType.Alphanumeric && char.IsDigit(ch)) 
       || (type == ChunkType.Numeric && !char.IsDigit(ch))) 
      { 
       return false; 
      } 

      return true; 
     } 

     public int Compare(object x, object y) 
     { 
      String s1 = x as string; 
      String s2 = y as string; 
      if (s1 == null || s2 == null) 
      { 
       return 0; 
      } 

      int thisMarker = 0, thisNumericChunk = 0; 
      int thatMarker = 0, thatNumericChunk = 0; 

      while ((thisMarker < s1.Length) || (thatMarker < s2.Length)) 
      { 
       if (thisMarker >= s1.Length) 
       { 
        return -1; 
       } 
       else if (thatMarker >= s2.Length) 
       { 
        return 1; 
       } 
       char thisCh = s1[thisMarker]; 
       char thatCh = s2[thatMarker]; 

       StringBuilder thisChunk = new StringBuilder(); 
       StringBuilder thatChunk = new StringBuilder(); 

       while ((thisMarker < s1.Length) && (thisChunk.Length==0 ||InChunk(thisCh, thisChunk[0]))) 
       { 
        thisChunk.Append(thisCh); 
        thisMarker++; 

        if (thisMarker < s1.Length) 
        { 
         thisCh = s1[thisMarker]; 
        } 
       } 

       while ((thatMarker < s2.Length) && (thatChunk.Length==0 ||InChunk(thatCh, thatChunk[0]))) 
       { 
        thatChunk.Append(thatCh); 
        thatMarker++; 

        if (thatMarker < s2.Length) 
        { 
         thatCh = s2[thatMarker]; 
        } 
       } 

       int result = 0; 
       // If both chunks contain numeric characters, sort them numerically 
       if (char.IsDigit(thisChunk[0]) && char.IsDigit(thatChunk[0])) 
       { 
        thisNumericChunk = Convert.ToInt32(thisChunk.ToString()); 
        thatNumericChunk = Convert.ToInt32(thatChunk.ToString()); 

        if (thisNumericChunk < thatNumericChunk) 
        { 
         result = -1; 
        } 

        if (thisNumericChunk > thatNumericChunk) 
        { 
         result = 1; 
        } 
       } 
       else 
       { 
        result = thisChunk.ToString().CompareTo(thatChunk.ToString()); 
       } 

       if (result != 0) 
       { 
        return result; 
       } 
      } 

      return 0; 
     } 
    } 
} 

Answer 5

On ne peut pas faire comme ceci:

public class MyComparer : IComparer<string> 
{ 

    public int Compare(string stringA, string stringB) 
    { 
     string small = stringA; 
     string big = stringB; 
     if (stringA.Length > stringB.Length) 
     { 
      small = stringB; 
      big = stringA; 
     } 
     else if (stringA.Length < stringB.Length) 
     { 
      small = stringA; 
      big = stringB; 
     } 
     for (int j = 0; j < small.Length; j++) 
     { 
      if (Convert.ToInt32(small[j]) > Convert.ToInt32(big[j])) return -1; 
      if (Convert.ToInt32(small[j]) < Convert.ToInt32(big[j])) return 1; 
     } 

     //big is indeed bigger 
     if (big.Length > small.Length) return 1; 

     //finally they are smae 
     return 0; 
    } 
} 

Utilisation:

string[] inputStrings = {"_abc*&","#almnp","abc" }; 
//string[] inputStrings = { "#", "_", "_a", "@", "_" }; 
MyComparer computer = new MyComparer(); 
var kola = inputStrings.OrderBy(x => x, new MyComparer()).ToArray(); 

C'est le même que:

Array.Sort(inputStrings, StringComparer.Ordinal);