Utiliser son propre IComparer <T> avec Linq OrderBy
J'ai un générique
List<MyClass>
où MyClass a 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, le comparateur par défaut trie (comme supposé) comme ceci:
200906/1
200906/10
200906/11
200906/12
200906/2
ce qui est méchant dans ce cas.
Maintenant, je veux utiliser mon propre IComparer<T> Avec cela. Cela 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 changé le code ApplySortCore pour utiliser ce IComparer:
case ListSortDirection.Ascending:
MyComparer comparer = new MyComparer();
items = items.OrderByDescending(
x => property.GetValue(x), comparer).ToList();
break;
Lorsque je débogue mon code, je vois que MyComparer.Compare(object, object) est appelée plusieurs fois et renvoie les bonnes valeurs (-1, 0, 1) pour une méthode de comparaison.
Mais ma liste est toujours triée dans le "mauvais" sens. Suis-je en train de manquer quelque chose? Je n'ai aucune idée.
Votre comparateur me semble faux. Vous êtes toujours en train de trier dans l'ordre de texte par défaut. Vous voulez sûrement analyser les deux nombres et trier en fonction de cela:
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 correspond pas bien à votre question indiquant que vous avez débogué et vérifié que Compare renvoie la bonne valeur - mais je crains de suspecter une erreur humaine sur ce front.)
De plus, Sven a raison - changer la valeur de items ne change pas du tout votre liste de bornes. Vous devez ajouter:
this.Items = items;
au fond de votre méthode.
J'ai rencontré le problème du tri naturel général et j'ai blogué la solution ici:
Tri naturel Comparer avec 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;
}
}
Vous pouvez utiliser l'algorithme Alphanum:
(...)
items.OrderBy(x => property.GetValue(x), new 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 <[email protected]>
*
* Adapted by Dominik Hurnaus <[email protected]> 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;
}
}
}
Ne pouvons-nous pas faire comme ça:
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;
}
}
Usage:
string[] inputStrings = {"_abc*&","#almnp","abc" };
//string[] inputStrings = { "#", "_", "_a", "@", "_" };
MyComparer computer = new MyComparer();
var kola = inputStrings.OrderBy(x => x, new MyComparer()).ToArray();
C'est la même chose que:
Array.Sort(inputStrings, StringComparer.Ordinal);
La liste triée est uniquement liée aux éléments de variable locaux, pas à la propriété Items de votre liste de liaisons, elle n'est donc pas triée.
[Edit] Fondamentalement, vous jetez simplement le résultat de vos efforts de tri ;-)