C# 中的自然排序顺序
本文关键字：排序 顺序 自然 | 更新日期: 2023-09-27 17:47:46
有人有很好的资源或为 FileInfo 数组提供 C# 中自然顺序排序的示例吗？ 我正在以我的排序实现IComparer接口。
最简单的
方法是在Windows中P/调用内置函数，并将其用作IComparer中的比较函数：
[DllImport("shlwapi.dll", CharSet = CharSet.Unicode)]
private static extern int StrCmpLogicalW(string psz1, string psz2);
Michael Kaplan 在这里有一些关于这个函数如何工作的例子，以及为 Vista 所做的更改，使其更直观地工作。此功能的优点是它将具有与运行它的Windows版本相同的行为，但是这确实意味着它因Windows版本而异，因此您需要考虑这是否是您的问题。
因此，完整的实现将是这样的：
[SuppressUnmanagedCodeSecurity]
internal static class SafeNativeMethods
{
[DllImport("shlwapi.dll", CharSet = CharSet.Unicode)]
public static extern int StrCmpLogicalW(string psz1, string psz2);
}
public sealed class NaturalStringComparer : IComparer<string>
{
public int Compare(string a, string b)
{
return SafeNativeMethods.StrCmpLogicalW(a, b);
}
}
public sealed class NaturalFileInfoNameComparer : IComparer<FileInfo>
{
public int Compare(FileInfo a, FileInfo b)
{
return SafeNativeMethods.StrCmpLogicalW(a.Name, b.Name);
}
}
只是想我会添加这个(使用我能找到的最简洁的解决方案(：
public static IOrderedEnumerable<T> OrderByAlphaNumeric<T>(this IEnumerable<T> source, Func<T, string> selector)
{
int max = source
.SelectMany(i => Regex.Matches(selector(i), @"'d+").Cast<Match>().Select(m => (int?)m.Value.Length))
.Max() ?? 0;
return source.OrderBy(i => Regex.Replace(selector(i), @"'d+", m => m.Value.PadLeft(max, '0')));
}
上面将字符串中的任何数字填充到所有字符串中所有数字的最大长度，并使用生成的字符串进行排序。
强制转换为(int?(是为了允许没有任何数字的字符串集合(.Max()在空的可枚举对象上抛出一个InvalidOperationException(。
现有的实现看起来都不是很好，所以我自己写了。 结果几乎与现代版本的 Windows 资源管理器 (Windows 7/8( 使用的排序相同。 我看到的唯一区别是 1( 虽然 Windows 曾经(例如 XP(处理任何长度的数字，但现在它仅限于 19 位数字 - 我的是无限的，2( Windows 与某些 Unicode 数字集给出不一致的结果 - 我的工作正常(尽管它没有从数字上比较代理对中的数字;Windows 也没有(，以及 3( 如果不同类型的非主要排序权重出现在不同的部分(例如"e-1é"与"é1e-" -数字前后的部分具有音调符号和标点符号粗细差异(。
public static int CompareNatural(string strA, string strB) {
return CompareNatural(strA, strB, CultureInfo.CurrentCulture, CompareOptions.IgnoreCase);
}
public static int CompareNatural(string strA, string strB, CultureInfo culture, CompareOptions options) {
CompareInfo cmp = culture.CompareInfo;
int iA = 0;
int iB = 0;
int softResult = 0;
int softResultWeight = 0;
while (iA < strA.Length && iB < strB.Length) {
bool isDigitA = Char.IsDigit(strA[iA]);
bool isDigitB = Char.IsDigit(strB[iB]);
if (isDigitA != isDigitB) {
return cmp.Compare(strA, iA, strB, iB, options);
}
else if (!isDigitA && !isDigitB) {
int jA = iA + 1;
int jB = iB + 1;
while (jA < strA.Length && !Char.IsDigit(strA[jA])) jA++;
while (jB < strB.Length && !Char.IsDigit(strB[jB])) jB++;
int cmpResult = cmp.Compare(strA, iA, jA - iA, strB, iB, jB - iB, options);
if (cmpResult != 0) {
// Certain strings may be considered different due to "soft" differences that are
// ignored if more significant differences follow, e.g. a hyphen only affects the
// comparison if no other differences follow
string sectionA = strA.Substring(iA, jA - iA);
string sectionB = strB.Substring(iB, jB - iB);
if (cmp.Compare(sectionA + "1", sectionB + "2", options) ==
cmp.Compare(sectionA + "2", sectionB + "1", options))
{
return cmp.Compare(strA, iA, strB, iB, options);
}
else if (softResultWeight < 1) {
softResult = cmpResult;
softResultWeight = 1;
}
}
iA = jA;
iB = jB;
}
else {
char zeroA = (char)(strA[iA] - (int)Char.GetNumericValue(strA[iA]));
char zeroB = (char)(strB[iB] - (int)Char.GetNumericValue(strB[iB]));
int jA = iA;
int jB = iB;
while (jA < strA.Length && strA[jA] == zeroA) jA++;
while (jB < strB.Length && strB[jB] == zeroB) jB++;
int resultIfSameLength = 0;
do {
isDigitA = jA < strA.Length && Char.IsDigit(strA[jA]);
isDigitB = jB < strB.Length && Char.IsDigit(strB[jB]);
int numA = isDigitA ? (int)Char.GetNumericValue(strA[jA]) : 0;
int numB = isDigitB ? (int)Char.GetNumericValue(strB[jB]) : 0;
if (isDigitA && (char)(strA[jA] - numA) != zeroA) isDigitA = false;
if (isDigitB && (char)(strB[jB] - numB) != zeroB) isDigitB = false;
if (isDigitA && isDigitB) {
if (numA != numB && resultIfSameLength == 0) {
resultIfSameLength = numA < numB ? -1 : 1;
}
jA++;
jB++;
}
}
while (isDigitA && isDigitB);
if (isDigitA != isDigitB) {
// One number has more digits than the other (ignoring leading zeros) - the longer
// number must be larger
return isDigitA ? 1 : -1;
}
else if (resultIfSameLength != 0) {
// Both numbers are the same length (ignoring leading zeros) and at least one of
// the digits differed - the first difference determines the result
return resultIfSameLength;
}
int lA = jA - iA;
int lB = jB - iB;
if (lA != lB) {
// Both numbers are equivalent but one has more leading zeros
return lA > lB ? -1 : 1;
}
else if (zeroA != zeroB && softResultWeight < 2) {
softResult = cmp.Compare(strA, iA, 1, strB, iB, 1, options);
softResultWeight = 2;
}
iA = jA;
iB = jB;
}
}
if (iA < strA.Length || iB < strB.Length) {
return iA < strA.Length ? 1 : -1;
}
else if (softResult != 0) {
return softResult;
}
return 0;
}
签名与Comparison<string>委托匹配：
string[] files = Directory.GetFiles(@"C:'");
Array.Sort(files, CompareNatural);
下面是一个用作IComparer<string>的包装类：
public class CustomComparer<T> : IComparer<T> {
private Comparison<T> _comparison;
public CustomComparer(Comparison<T> comparison) {
_comparison = comparison;
}
public int Compare(T x, T y) {
return _comparison(x, y);
}
}
例：
string[] files = Directory.EnumerateFiles(@"C:'")
.OrderBy(f => f, new CustomComparer<string>(CompareNatural))
.ToArray();
以下是我用于测试的一组很好的文件名：
Func<string, string> expand = (s) => { int o; while ((o = s.IndexOf('''')) != -1) { int p = o + 1;
int z = 1; while (s[p] == '0') { z++; p++; } int c = Int32.Parse(s.Substring(p, z));
s = s.Substring(0, o) + new string(s[o - 1], c) + s.Substring(p + z); } return s; };
string encodedFileNames =
"KDEqLW4xMiotbjEzKjAwMDFcMDY2KjAwMlwwMTcqMDA5XDAxNyowMlwwMTcqMDlcMDE3KjEhKjEtISox" +
"LWEqMS4yNT8xLjI1KjEuNT8xLjUqMSoxXDAxNyoxXDAxOCoxXDAxOSoxXDA2NioxXDA2NyoxYSoyXDAx" +
"NyoyXDAxOCo5XDAxNyo5XDAxOCo5XDA2Nio9MSphMDAxdGVzdDAxKmEwMDF0ZXN0aW5nYTBcMzEqYTAw" +
"Mj9hMDAyIGE/YTAwMiBhKmEwMDIqYTAwMmE/YTAwMmEqYTAxdGVzdGluZ2EwMDEqYTAxdnNmcyphMSph" +
"MWEqYTF6KmEyKmIwMDAzcTYqYjAwM3E0KmIwM3E1KmMtZSpjZCpjZipmIDEqZipnP2cgMT9oLW4qaG8t" +
"bipJKmljZS1jcmVhbT9pY2VjcmVhbT9pY2VjcmVhbS0/ajBcNDE/ajAwMWE/ajAxP2shKmsnKmstKmsx" +
"KmthKmxpc3QqbTAwMDNhMDA1YSptMDAzYTAwMDVhKm0wMDNhMDA1Km0wMDNhMDA1YSpuMTIqbjEzKm8t" +
"bjAxMypvLW4xMipvLW40P28tbjQhP28tbjR6P28tbjlhLWI1Km8tbjlhYjUqb24wMTMqb24xMipvbjQ/" +
"b240IT9vbjR6P29uOWEtYjUqb245YWI1Km/CrW4wMTMqb8KtbjEyKnAwMCpwMDEqcDAxwr0hKnAwMcK9" +
"KnAwMcK9YSpwMDHCvcK+KnAwMipwMMK9KnEtbjAxMypxLW4xMipxbjAxMypxbjEyKnItMDAhKnItMDAh" +
"NSpyLTAwIe+8lSpyLTAwYSpyLe+8kFwxIS01KnIt77yQXDEhLe+8lSpyLe+8kFwxISpyLe+8kFwxITUq" +
"ci3vvJBcMSHvvJUqci3vvJBcMWEqci3vvJBcMyE1KnIwMCEqcjAwLTUqcjAwLjUqcjAwNSpyMDBhKnIw" +
"NSpyMDYqcjQqcjUqctmg2aYqctmkKnLZpSpy27Dbtipy27Qqctu1KnLfgN+GKnLfhCpy34UqcuClpuCl" +
"rCpy4KWqKnLgpasqcuCnpuCnrCpy4KeqKnLgp6sqcuCppuCprCpy4KmqKnLgqasqcuCrpuCrrCpy4Kuq" +
"KnLgq6sqcuCtpuCtrCpy4K2qKnLgrasqcuCvpuCvrCpy4K+qKnLgr6sqcuCxpuCxrCpy4LGqKnLgsasq" +
"cuCzpuCzrCpy4LOqKnLgs6sqcuC1puC1rCpy4LWqKnLgtasqcuC5kOC5lipy4LmUKnLguZUqcuC7kOC7" +
"lipy4LuUKnLgu5UqcuC8oOC8pipy4LykKnLgvKUqcuGBgOGBhipy4YGEKnLhgYUqcuGCkOGClipy4YKU" +
"KnLhgpUqcuGfoOGfpipy4Z+kKnLhn6UqcuGgkOGglipy4aCUKnLhoJUqcuGlhuGljCpy4aWKKnLhpYsq" +
"cuGnkOGnlipy4aeUKnLhp5UqcuGtkOGtlipy4a2UKnLhrZUqcuGusOGutipy4a60KnLhrrUqcuGxgOGx" +
"hipy4bGEKnLhsYUqcuGxkOGxlipy4bGUKnLhsZUqcuqYoFwx6pilKnLqmKDqmKUqcuqYoOqYpipy6pik" +
"KnLqmKUqcuqjkOqjlipy6qOUKnLqo5UqcuqkgOqkhipy6qSEKnLqpIUqcuqpkOqplipy6qmUKnLqqZUq" +
"cvCQkqAqcvCQkqUqcvCdn5gqcvCdn50qcu+8kFwxISpy77yQXDEt77yVKnLvvJBcMS7vvJUqcu+8kFwx" +
"YSpy77yQXDHqmKUqcu+8kFwx77yO77yVKnLvvJBcMe+8lSpy77yQ77yVKnLvvJDvvJYqcu+8lCpy77yV" +
"KnNpKnPEsSp0ZXN02aIqdGVzdNmi2aAqdGVzdNmjKnVBZS0qdWFlKnViZS0qdUJlKnVjZS0xw6kqdWNl" +
"McOpLSp1Y2Uxw6kqdWPDqS0xZSp1Y8OpMWUtKnVjw6kxZSp3ZWlhMSp3ZWlhMip3ZWlzczEqd2Vpc3My" +
"KndlaXoxKndlaXoyKndlacOfMSp3ZWnDnzIqeSBhMyp5IGE0KnknYTMqeSdhNCp5K2EzKnkrYTQqeS1h" +
"Myp5LWE0KnlhMyp5YTQqej96IDA1MD96IDIxP3ohMjE/ejIwP3oyMj96YTIxP3rCqTIxP1sxKl8xKsKt" +
"bjEyKsKtbjEzKsSwKg==";
string[] fileNames = Encoding.UTF8.GetString(Convert.FromBase64String(encodedFileNames))
.Replace("*", ".txt?").Split(new[] { "?" }, StringSplitOptions.RemoveEmptyEntries)
.Select(n => expand(n)).ToArray();
Matthews Horsleys 的答案是最快的方法，它不会根据程序运行的 Windows 版本而改变行为。但是，通过创建一次正则表达式并使用RegexOptions.Compiled，它可以更快。我还添加了插入字符串比较器的选项，以便您可以在需要时忽略大小写，并稍微提高了可读性。
public static IEnumerable<T> OrderByNatural<T>(this IEnumerable<T> items, Func<T, string> selector, StringComparer stringComparer = null)
{
var regex = new Regex(@"'d+", RegexOptions.Compiled);
int maxDigits = items
.SelectMany(i => regex.Matches(selector(i)).Cast<Match>().Select(digitChunk => (int?)digitChunk.Value.Length))
.Max() ?? 0;
return items.OrderBy(i => regex.Replace(selector(i), match => match.Value.PadLeft(maxDigits, '0')), stringComparer ?? StringComparer.CurrentCulture);
}
使用者使用
var sortedEmployees = employees.OrderByNatural(emp => emp.Name);
对 100,000 个字符串进行排序需要 450 毫秒，而默认的 .net 字符串比较需要 300 毫秒 - 非常快！
用于 linq orderby 的纯 C# 解决方案：
http://zootfroot.blogspot.com/2009/09/natural-sort-compare-with-linq-orderby.html
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;
}
}
我的解决方案：
void Main()
{
new[] {"a4","a3","a2","a10","b5","b4","b400","1","C1d","c1d2"}.OrderBy(x => x, new NaturalStringComparer()).Dump();
}
public class NaturalStringComparer : IComparer<string>
{
private static readonly Regex _re = new Regex(@"(?<='D)(?='d)|(?<='d)(?='D)", RegexOptions.Compiled);
public int Compare(string x, string y)
{
x = x.ToLower();
y = y.ToLower();
if(string.Compare(x, 0, y, 0, Math.Min(x.Length, y.Length)) == 0)
{
if(x.Length == y.Length) return 0;
return x.Length < y.Length ? -1 : 1;
}
var a = _re.Split(x);
var b = _re.Split(y);
int i = 0;
while(true)
{
int r = PartCompare(a[i], b[i]);
if(r != 0) return r;
++i;
}
}
private static int PartCompare(string x, string y)
{
int a, b;
if(int.TryParse(x, out a) && int.TryParse(y, out b))
return a.CompareTo(b);
return x.CompareTo(y);
}
}
结果：
1
a2
a3
a4
a10
b4
b5
b400
C1d
c1d2
你确实需要小心 - 我依稀记得读过StrCmpLogicalW或类似的东西，不是严格传递的，我已经观察到。NET 的排序方法有时会在比较函数违反该规则时陷入无限循环。
传递比较将始终报告如果 a <c，则>
这是我对同时具有字母和数字字符的字符串进行排序的代码。
首先，这种扩展方法：
public static IEnumerable<string> AlphanumericSort(this IEnumerable<string> me)
{
return me.OrderBy(x => Regex.Replace(x, @"'d+", m => m.Value.PadLeft(50, '0')));
}
然后，只需在代码中的任何位置使用它，如下所示：
List<string> test = new List<string>() { "The 1st", "The 12th", "The 2nd" };
test = test.AlphanumericSort();
它是如何工作的？通过替换为零：
Original | Regex Replace | The | Returned
List | Apply PadLeft | Sorting | List
| | |
"The 1st" | "The 001st" | "The 001st" | "The 1st"
"The 12th" | "The 012th" | "The 002nd" | "The 2nd"
"The 2nd" | "The 002nd" | "The 012th" | "The 12th"
适用于倍数：
Alphabetical Sorting | Alphanumeric Sorting
|
"Page 21, Line 42" | "Page 3, Line 7"
"Page 21, Line 5" | "Page 3, Line 32"
"Page 3, Line 32" | "Page 21, Line 5"
"Page 3, Line 7" | "Page 21, Line 42"
希望这会有所帮助。
这是 .NET Core 2.1+/.NET 5.0+ 的版本，使用跨度来避免分配
public class NaturalSortStringComparer : IComparer<string>
{
public static NaturalSortStringComparer Ordinal { get; } = new NaturalSortStringComparer(StringComparison.Ordinal);
public static NaturalSortStringComparer OrdinalIgnoreCase { get; } = new NaturalSortStringComparer(StringComparison.OrdinalIgnoreCase);
public static NaturalSortStringComparer CurrentCulture { get; } = new NaturalSortStringComparer(StringComparison.CurrentCulture);
public static NaturalSortStringComparer CurrentCultureIgnoreCase { get; } = new NaturalSortStringComparer(StringComparison.CurrentCultureIgnoreCase);
public static NaturalSortStringComparer InvariantCulture { get; } = new NaturalSortStringComparer(StringComparison.InvariantCulture);
public static NaturalSortStringComparer InvariantCultureIgnoreCase { get; } = new NaturalSortStringComparer(StringComparison.InvariantCultureIgnoreCase);
private readonly StringComparison _comparison;
public NaturalSortStringComparer(StringComparison comparison)
{
_comparison = comparison;
}
public int Compare(string x, string y)
{
// Let string.Compare handle the case where x or y is null
if (x is null || y is null)
return string.Compare(x, y, _comparison);
var xSegments = GetSegments(x);
var ySegments = GetSegments(y);
while (xSegments.MoveNext() && ySegments.MoveNext())
{
int cmp;
// If they're both numbers, compare the value
if (xSegments.CurrentIsNumber && ySegments.CurrentIsNumber)
{
var xValue = long.Parse(xSegments.Current);
var yValue = long.Parse(ySegments.Current);
cmp = xValue.CompareTo(yValue);
if (cmp != 0)
return cmp;
}
// If x is a number and y is not, x is "lesser than" y
else if (xSegments.CurrentIsNumber)
{
return -1;
}
// If y is a number and x is not, x is "greater than" y
else if (ySegments.CurrentIsNumber)
{
return 1;
}
// OK, neither are number, compare the segments as text
cmp = xSegments.Current.CompareTo(ySegments.Current, _comparison);
if (cmp != 0)
return cmp;
}
// At this point, either all segments are equal, or one string is shorter than the other
// If x is shorter, it's "lesser than" y
if (x.Length < y.Length)
return -1;
// If x is longer, it's "greater than" y
if (x.Length > y.Length)
return 1;
// If they have the same length, they're equal
return 0;
}
private static StringSegmentEnumerator GetSegments(string s) => new StringSegmentEnumerator(s);
private struct StringSegmentEnumerator
{
private readonly string _s;
private int _start;
private int _length;
public StringSegmentEnumerator(string s)
{
_s = s;
_start = -1;
_length = 0;
CurrentIsNumber = false;
}
public ReadOnlySpan<char> Current => _s.AsSpan(_start, _length);
public bool CurrentIsNumber { get; private set; }
public bool MoveNext()
{
var currentPosition = _start >= 0
? _start + _length
: 0;
if (currentPosition >= _s.Length)
return false;
int start = currentPosition;
bool isFirstCharDigit = Char.IsDigit(_s[currentPosition]);
while (++currentPosition < _s.Length && Char.IsDigit(_s[currentPosition]) == isFirstCharDigit)
{
}
_start = start;
_length = currentPosition - start;
CurrentIsNumber = isFirstCharDigit;
return true;
}
}
}
下面是一个相对简单的示例，它不使用 P/Invoke 并避免在执行期间进行任何分配。
请随意使用此处的代码，或者如果更容易，可以使用 NuGet 包：
https://www.nuget.org/packages/NaturalSort
https://github.com/drewnoakes/natural-sort
internal sealed class NaturalStringComparer : IComparer<string>
{
public static NaturalStringComparer Instance { get; } = new NaturalStringComparer();
public int Compare(string x, string y)
{
// sort nulls to the start
if (x == null)
return y == null ? 0 : -1;
if (y == null)
return 1;
var ix = 0;
var iy = 0;
while (true)
{
// sort shorter strings to the start
if (ix >= x.Length)
return iy >= y.Length ? 0 : -1;
if (iy >= y.Length)
return 1;
var cx = x[ix];
var cy = y[iy];
int result;
if (char.IsDigit(cx) && char.IsDigit(cy))
result = CompareInteger(x, y, ref ix, ref iy);
else
result = cx.CompareTo(y[iy]);
if (result != 0)
return result;
ix++;
iy++;
}
}
private static int CompareInteger(string x, string y, ref int ix, ref int iy)
{
var lx = GetNumLength(x, ix);
var ly = GetNumLength(y, iy);
// shorter number first (note, doesn't handle leading zeroes)
if (lx != ly)
return lx.CompareTo(ly);
for (var i = 0; i < lx; i++)
{
var result = x[ix++].CompareTo(y[iy++]);
if (result != 0)
return result;
}
return 0;
}
private static int GetNumLength(string s, int i)
{
var length = 0;
while (i < s.Length && char.IsDigit(s[i++]))
length++;
return length;
}
}
它不会忽略前导零，因此01在 2 之后。
对应单元测试：
public class NumericStringComparerTests
{
[Fact]
public void OrdersCorrectly()
{
AssertEqual("", "");
AssertEqual(null, null);
AssertEqual("Hello", "Hello");
AssertEqual("Hello123", "Hello123");
AssertEqual("123", "123");
AssertEqual("123Hello", "123Hello");
AssertOrdered("", "Hello");
AssertOrdered(null, "Hello");
AssertOrdered("Hello", "Hello1");
AssertOrdered("Hello123", "Hello124");
AssertOrdered("Hello123", "Hello133");
AssertOrdered("Hello123", "Hello223");
AssertOrdered("123", "124");
AssertOrdered("123", "133");
AssertOrdered("123", "223");
AssertOrdered("123", "1234");
AssertOrdered("123", "2345");
AssertOrdered("0", "1");
AssertOrdered("123Hello", "124Hello");
AssertOrdered("123Hello", "133Hello");
AssertOrdered("123Hello", "223Hello");
AssertOrdered("123Hello", "1234Hello");
}
private static void AssertEqual(string x, string y)
{
Assert.Equal(0, NaturalStringComparer.Instance.Compare(x, y));
Assert.Equal(0, NaturalStringComparer.Instance.Compare(y, x));
}
private static void AssertOrdered(string x, string y)
{
Assert.Equal(-1, NaturalStringComparer.Instance.Compare(x, y));
Assert.Equal( 1, NaturalStringComparer.Instance.Compare(y, x));
}
}
除了 Greg Beech 的答案(因为我一直在寻找它(，如果你想从 Linq 使用它，你可以使用需要IComparer OrderBy。 例如：
var items = new List<MyItem>();
// fill items
var sorted = items.OrderBy(item => item.Name, new NaturalStringComparer());
我实际上已经将其实现为StringComparer上的扩展方法，以便您可以执行以下操作：
-
StringComparer.CurrentCulture.WithNaturalSort()或 -
StringComparer.OrdinalIgnoreCase.WithNaturalSort().
由此产生的IComparer<string>可用于所有地方，如OrderBy、OrderByDescending、ThenBy、ThenByDescending、SortedSet<string>等。而且您仍然可以轻松调整区分大小写、区域性等。
该实现相当简单，即使在大序列上也应该表现得很好。
<小时 />我还将其发布为一个很小的 NuGet 包，因此您可以执行以下操作：
Install-Package NaturalSort.Extension
包含XML文档注释和测试套件的代码可在NaturalSort.Extension GitHub存储库中找到。
<小时 />整个代码是这样的(如果还不能使用 C# 7，只需安装 NuGet 包(：
public static class StringComparerNaturalSortExtension
{
public static IComparer<string> WithNaturalSort(this StringComparer stringComparer) => new NaturalSortComparer(stringComparer);
private class NaturalSortComparer : IComparer<string>
{
public NaturalSortComparer(StringComparer stringComparer)
{
_stringComparer = stringComparer;
}
private readonly StringComparer _stringComparer;
private static readonly Regex NumberSequenceRegex = new Regex(@"('d+)", RegexOptions.Compiled | RegexOptions.CultureInvariant);
private static string[] Tokenize(string s) => s == null ? new string[] { } : NumberSequenceRegex.Split(s);
private static ulong ParseNumberOrZero(string s) => ulong.TryParse(s, NumberStyles.None, CultureInfo.InvariantCulture, out var result) ? result : 0;
public int Compare(string s1, string s2)
{
var tokens1 = Tokenize(s1);
var tokens2 = Tokenize(s2);
var zipCompare = tokens1.Zip(tokens2, TokenCompare).FirstOrDefault(x => x != 0);
if (zipCompare != 0)
return zipCompare;
var lengthCompare = tokens1.Length.CompareTo(tokens2.Length);
return lengthCompare;
}
private int TokenCompare(string token1, string token2)
{
var number1 = ParseNumberOrZero(token1);
var number2 = ParseNumberOrZero(token2);
var numberCompare = number1.CompareTo(number2);
if (numberCompare != 0)
return numberCompare;
var stringCompare = _stringComparer.Compare(token1, token2);
return stringCompare;
}
}
}
受 Michael Parker 解决方案的启发，下面是一个IComparer实现，您可以将其放入任何 linq 排序方法中：
private class NaturalStringComparer : IComparer<string>
{
public int Compare(string left, string right)
{
int max = new[] { left, right }
.SelectMany(x => Regex.Matches(x, @"'d+").Cast<Match>().Select(y => (int?)y.Value.Length))
.Max() ?? 0;
var leftPadded = Regex.Replace(left, @"'d+", m => m.Value.PadLeft(max, '0'));
var rightPadded = Regex.Replace(right, @"'d+", m => m.Value.PadLeft(max, '0'));
return string.Compare(leftPadded, rightPadded);
}
}
这是一个天真的单行无正则表达式 LINQ 方式(借用自 python(：
var alphaStrings = new List<string>() { "10","2","3","4","50","11","100","a12","b12" };
var orderedString = alphaStrings.OrderBy(g => new Tuple<int, string>(g.ToCharArray().All(char.IsDigit)? int.Parse(g) : int.MaxValue, g));
// Order Now: ["2","3","4","10","11","50","100","a12","b12"]
扩展了前面的几个答案并利用了扩展方法，我想出了以下内容，它没有潜在的多个可枚举枚举的警告，或者与使用多个正则表达式对象或不必要地调用正则表达式相关的性能问题，话虽如此，它确实使用了 ToList((，这可能会抵消较大集合的好处。
选择器支持泛型类型以允许分配任何委托，源集合中的元素由选择器改变，然后使用 ToString(( 转换为字符串。
private static readonly Regex _NaturalOrderExpr = new Regex(@"'d+", RegexOptions.Compiled);
public static IEnumerable<TSource> OrderByNatural<TSource, TKey>(
this IEnumerable<TSource> source, Func<TSource, TKey> selector)
{
int max = 0;
var selection = source.Select(
o =>
{
var v = selector(o);
var s = v != null ? v.ToString() : String.Empty;
if (!String.IsNullOrWhiteSpace(s))
{
var mc = _NaturalOrderExpr.Matches(s);
if (mc.Count > 0)
{
max = Math.Max(max, mc.Cast<Match>().Max(m => m.Value.Length));
}
}
return new
{
Key = o,
Value = s
};
}).ToList();
return
selection.OrderBy(
o =>
String.IsNullOrWhiteSpace(o.Value) ? o.Value : _NaturalOrderExpr.Replace(o.Value, m => m.Value.PadLeft(max, '0')))
.Select(o => o.Key);
}
public static IEnumerable<TSource> OrderByDescendingNatural<TSource, TKey>(
this IEnumerable<TSource> source, Func<TSource, TKey> selector)
{
int max = 0;
var selection = source.Select(
o =>
{
var v = selector(o);
var s = v != null ? v.ToString() : String.Empty;
if (!String.IsNullOrWhiteSpace(s))
{
var mc = _NaturalOrderExpr.Matches(s);
if (mc.Count > 0)
{
max = Math.Max(max, mc.Cast<Match>().Max(m => m.Value.Length));
}
}
return new
{
Key = o,
Value = s
};
}).ToList();
return
selection.OrderByDescending(
o =>
String.IsNullOrWhiteSpace(o.Value) ? o.Value : _NaturalOrderExpr.Replace(o.Value, m => m.Value.PadLeft(max, '0')))
.Select(o => o.Key);
}
一个
更易于阅读/维护的版本。
public class NaturalStringComparer : IComparer<string>
{
public static NaturalStringComparer Instance { get; } = new NaturalStringComparer();
public int Compare(string x, string y) {
const int LeftIsSmaller = -1;
const int RightIsSmaller = 1;
const int Equal = 0;
var leftString = x;
var rightString = y;
var stringComparer = CultureInfo.CurrentCulture.CompareInfo;
int rightIndex;
int leftIndex;
for (leftIndex = 0, rightIndex = 0;
leftIndex < leftString.Length && rightIndex < rightString.Length;
leftIndex++, rightIndex++) {
var leftChar = leftString[leftIndex];
var rightChar = rightString[leftIndex];
var leftIsNumber = char.IsNumber(leftChar);
var rightIsNumber = char.IsNumber(rightChar);
if (!leftIsNumber && !rightIsNumber) {
var result = stringComparer.Compare(leftString, leftIndex, 1, rightString, leftIndex, 1);
if (result != 0) return result;
} else if (leftIsNumber && !rightIsNumber) {
return LeftIsSmaller;
} else if (!leftIsNumber && rightIsNumber) {
return RightIsSmaller;
} else {
var leftNumberLength = NumberLength(leftString, leftIndex, out var leftNumber);
var rightNumberLength = NumberLength(rightString, rightIndex, out var rightNumber);
if (leftNumberLength < rightNumberLength) {
return LeftIsSmaller;
} else if (leftNumberLength > rightNumberLength) {
return RightIsSmaller;
} else {
if(leftNumber < rightNumber) {
return LeftIsSmaller;
} else if(leftNumber > rightNumber) {
return RightIsSmaller;
}
}
}
}
if (leftString.Length < rightString.Length) {
return LeftIsSmaller;
} else if(leftString.Length > rightString.Length) {
return RightIsSmaller;
}
return Equal;
}
public int NumberLength(string str, int offset, out int number) {
if (string.IsNullOrWhiteSpace(str)) throw new ArgumentNullException(nameof(str));
if (offset >= str.Length) throw new ArgumentOutOfRangeException(nameof(offset), offset, "Offset must be less than the length of the string.");
var currentOffset = offset;
var curChar = str[currentOffset];
if (!char.IsNumber(curChar))
throw new ArgumentException($"'{curChar}' is not a number.", nameof(offset));
int length = 1;
var numberString = string.Empty;
for (currentOffset = offset + 1;
currentOffset < str.Length;
currentOffset++, length++) {
curChar = str[currentOffset];
numberString += curChar;
if (!char.IsNumber(curChar)) {
number = int.Parse(numberString);
return length;
}
}
number = int.Parse(numberString);
return length;
}
}
我们需要一种自然排序来处理具有以下模式的文本：
"Test 1-1-1 something"
"Test 1-2-3 something"
...
出于某种原因，当我第一次查看SO时，我没有找到这篇文章并实现了我们自己的帖子。与这里介绍的一些解决方案相比，虽然在概念上相似，但它的好处是可能更简单、更容易理解。但是，虽然我确实尝试查看性能瓶颈，但它的实现速度仍然比默认OrderBy()慢得多。
这是我实现的扩展方法：
public static class EnumerableExtensions
{
// set up the regex parser once and for all
private static readonly Regex Regex = new Regex(@"'d+|'D+", RegexOptions.Compiled | RegexOptions.Singleline);
// stateless comparer can be built once
private static readonly AggregateComparer Comparer = new AggregateComparer();
public static IEnumerable<T> OrderByNatural<T>(this IEnumerable<T> source, Func<T, string> selector)
{
// first extract string from object using selector
// then extract digit and non-digit groups
Func<T, IEnumerable<IComparable>> splitter =
s => Regex.Matches(selector(s))
.Cast<Match>()
.Select(m => Char.IsDigit(m.Value[0]) ? (IComparable) int.Parse(m.Value) : m.Value);
return source.OrderBy(splitter, Comparer);
}
/// <summary>
/// This comparer will compare two lists of objects against each other
/// </summary>
/// <remarks>Objects in each list are compare to their corresponding elements in the other
/// list until a difference is found.</remarks>
private class AggregateComparer : IComparer<IEnumerable<IComparable>>
{
public int Compare(IEnumerable<IComparable> x, IEnumerable<IComparable> y)
{
return
x.Zip(y, (a, b) => new {a, b}) // walk both lists
.Select(pair => pair.a.CompareTo(pair.b)) // compare each object
.FirstOrDefault(result => result != 0); // until a difference is found
}
}
}
这个想法是将原始字符串拆分为数字块和非数字块("'d+|'D+"(。由于这是一项可能昂贵的任务，因此每个条目仅执行一次。然后我们使用可比较对象的比较器(对不起，我找不到更合适的表达方式(。它将每个块与另一个字符串中的相应块进行比较。
我希望获得有关如何改进以及主要缺陷的反馈。请注意，在这一点上，可维护性对我们很重要，我们目前没有在非常大的数据集中使用它。
让我解释一下我的问题以及我是如何解决它的。
问题：- 根据从目录中检索的 FileInfo 对象的文件名对文件进行排序。
解决方案：- 我从FileInfo中选择文件名并修剪了文件名的".png"部分。现在，只需执行List.Sort((，它按自然排序顺序对文件名进行排序。根据我的测试，我发现.png会弄乱排序顺序。看看下面的代码
var imageNameList = new DirectoryInfo(@"C:'Temp'Images").GetFiles("*.png").Select(x =>x.Name.Substring(0, x.Name.Length - 4)).ToList();
imageNameList.Sort();