从列表C＃中删除项目＃

Question

我有两个对象列表，我必须删除其他列表中删除的值到'原始'列表中;但该项目由两个属性标识。 我能做到这一点，当对象仅由一个属性标识，但现在我需要检查两个属性

// library: object with deleted data 
// library = new List<Widget>() { new Widget() { Id = "1", Nbr = 1 }, new Widget() { Id = "3", Nbr = 2 } }; 
var allData = GetData(); 
// allData = new List<Widget>() { new Widget() { Id = "1", Nbr = 1 }, new Widget() { Id = "2", Nbr = 1 }, new Widget() { Id = "3", Nbr = 2 } }; 
// var itemsToDelete = allData.Where(w => library.All(p => p.Id != w.Id)).ToList(); // I would do this, if the identifier would be only Id 

var itemsToDelete = allData.Where(w => library.All(p => p.Id != w.Id && p.Nbr != w.Nbr)).ToList(); // I need to check for two properties and I'm getting zero coincidences 

Answer 1

var itemsToDelete = allData.Where(w => !library.Any(p => p.Id == w.Id && p.Nbr == w.Nbr)).ToList(); 

应该是正确的，但不是最佳的。 （O^2）