这里有两个扩展方法,可能在需要查找两个IEnumerable之间的无序差异时会很有用(它与leppie的答案大致相同,包装成了扩展方法):
public class EnumerableDifferences<T>
{
public IEnumerable<T> Added { get; }
public IEnumerable<T> Removed { get; }
public EnumerableDifferences(IEnumerable<T> added, IEnumerable<T> removed)
{
Added = added;
Removed = removed;
}
}
public static class EnumerableExtensions
{
public static HashSet<TSource> ToHashSet<TSource>(this IEnumerable<TSource> source, IEqualityComparer<TSource> comparer)
{
return new HashSet<TSource>(source, comparer);
}
public static IEnumerable<TSource> ExceptBy<TSource, TKey>(this IEnumerable<TSource> first, IEnumerable<TSource> second, Func<TSource, TKey> keySelector, IEqualityComparer<TKey> keyComparer = null)
{
return first
.ExceptBy(keySelector, second.Select(keySelector), keyComparer);
}
public static IEnumerable<TSource> ExceptBy<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector, IEnumerable<TKey> keys, IEqualityComparer<TKey> keyComparer = null)
{
var secondKeys = keys.ToHashSet(keyComparer);
foreach (var firstItem in source)
{
var firstItemKey = keySelector(firstItem);
if (!secondKeys.Contains(firstItemKey))
{
yield return firstItem;
}
}
}
public static EnumerableDifferences<TSource> DifferencesBy<TSource, TKey>(this IEnumerable<TSource> first, IEnumerable<TSource> second, Func<TSource, TKey> keySelector, IEqualityComparer<TKey> keyComparer = null)
{
keyComparer = keyComparer ?? EqualityComparer<TKey>.Default;
var removed = first.ExceptBy(second, keySelector, keyComparer);
var added = second.ExceptBy(first, keySelector, keyComparer);
var result = new EnumerableDifferences<TSource>(added, removed);
return result;
}
public static EnumerableDifferences<TSource> Differences<TSource>(this IEnumerable<TSource> first, IEnumerable<TSource> second, IEqualityComparer<TSource> comparer = null)
{
return first
.DifferencesBy(second, x => x, comparer);
}
}
public static class Program
{
public static void Main(params string[] args)
{
var l1 = new[] { 'a', 'b', 'c' };
var l2 = new[] { 'a', 'd', 'c' };
var result = l1.Differences(l2);
Console.ReadKey();
}
}