The opposite of Intersect()
本文关键字:Intersect of opposite The | 更新日期: 2023-09-27 17:49:35
Intersect可用于查找两个集合之间的匹配,如下所示:
// Assign two arrays.
int[] array1 = { 1, 2, 3 };
int[] array2 = { 2, 3, 4 };
// Call Intersect extension method.
var intersect = array1.Intersect(array2);
// Write intersection to screen.
foreach (int value in intersect)
{
Console.WriteLine(value); // Output: 2, 3
}
然而,我想实现的是相反的,我想列出一个集合中缺少的项::
// Assign two arrays.
int[] array1 = { 1, 2, 3 };
int[] array2 = { 2, 3, 4 };
// Call "NonIntersect" extension method.
var intersect = array1.NonIntersect(array2); // I've made up the NonIntersect method
// Write intersection to screen.
foreach (int value in intersect)
{
Console.WriteLine(value); // Output: 4
}
如前所述,如果您希望得到4作为结果,您可以这样做:
var nonintersect = array2.Except(array1);
如果你想要真正的非相交(也包括1和4),那么这个应该可以做到:
var nonintersect = array1.Except(array2).Union( array2.Except(array1));
这不是性能最好的解决方案,但对于小列表,它应该工作得很好。
可以使用
a.Except(b).Union(b.Except(a));
也可以用
var difference = new HashSet(a);
difference.SymmetricExceptWith(b);
此代码仅枚举每个序列一次,并使用Select(x => x)
隐藏结果以获得干净的linq风格扩展方法。由于它使用HashSet<T>
,如果散列分布良好,则运行时间为O(n + m)
。两个列表中的重复元素将被省略。
public static IEnumerable<T> SymmetricExcept<T>(this IEnumerable<T> seq1,
IEnumerable<T> seq2)
{
HashSet<T> hashSet = new HashSet<T>(seq1);
hashSet.SymmetricExceptWith(seq2);
return hashSet.Select(x => x);
}
我想你可能在找Except
:
Except操作符生成集合两个序列之间的差异。它只返回第一个元素吗序列中没有出现的第二。您可以选择提供你自己的相等比较函数。
查看这个链接,这个链接,或者谷歌,了解更多信息
array1.NonIntersect(array2);
Linq中不存在非相交操作符,您应该执行
except -> union -> except
a.except(b).union(b.Except(a));
我不是100%确定你的非相交方法应该做什么(关于集合理论)-它是
B ' A (B中没有出现在A中的一切)?
如果是,那么您应该能够使用Except操作(B.Except(A))。
/// <summary>
/// Given two list, compare and extract differences
/// http://stackoverflow.com/questions/5620266/the-opposite-of-intersect
/// </summary>
public class CompareList
{
/// <summary>
/// Returns list of items that are in initial but not in final list.
/// </summary>
/// <param name="listA"></param>
/// <param name="listB"></param>
/// <returns></returns>
public static IEnumerable<string> NonIntersect(
List<string> initial, List<string> final)
{
//subtracts the content of initial from final
//assumes that final.length < initial.length
return initial.Except(final);
}
/// <summary>
/// Returns the symmetric difference between the two list.
/// http://en.wikipedia.org/wiki/Symmetric_difference
/// </summary>
/// <param name="initial"></param>
/// <param name="final"></param>
/// <returns></returns>
public static IEnumerable<string> SymmetricDifference(
List<string> initial, List<string> final)
{
IEnumerable<string> setA = NonIntersect(final, initial);
IEnumerable<string> setB = NonIntersect(initial, final);
// sum and return the two set.
return setA.Concat(setB);
}
}
string left = "411329_SOFT_MAC_GREEN";
string right= "SOFT_MAC_GREEN";
string[] l = left.Split('_');
string[] r = right.Split('_');
string[] distinctLeft = l.Distinct().ToArray();
string[] distinctRight = r.Distinct().ToArray();
var commonWord = l.Except(r, StringComparer.OrdinalIgnoreCase)
string result = String.Join("_",commonWord);
result = "411329"