Question

目前我正在寻找有效的解决方案来解决如何使用linq过滤一个集合中不存在于其他集合中的项目。到目前为止，我提出了以下选项：

class ConrolAccount
        {
            public string ControlName { get; set; }

            public string NaturalAccount { get; set; }
        }

        static void Main(string[] args)
        {
            var defaultAccounts = new List<ConrolAccount>
            {
                new ConrolAccount {NaturalAccount = "71300", ControlName = "Income Control"},
                new ConrolAccount {NaturalAccount = "70900", ControlName = "AP Control"},
                new ConrolAccount {NaturalAccount = "71600", ControlName = "Cost Control"},
                new ConrolAccount {NaturalAccount = "20200", ControlName = "Trust Control"},
                new ConrolAccount {NaturalAccount = "71800", ControlName = "Tax Control"},
                new ConrolAccount {NaturalAccount = "72000", ControlName = "Undeposited Funds"}
            };

            var existingAccounts = new List<ConrolAccount>
            {
                new ConrolAccount {NaturalAccount = "70900", ControlName = "AP Control"},
                new ConrolAccount {NaturalAccount = "71600", ControlName = "Cost Control"},
                new ConrolAccount {NaturalAccount = "72000", ControlName = "Undeposited Funds"}
            };

            IEnumerable<string> missedAccounts = defaultAccounts
                .GroupJoin(existingAccounts, d => d.ControlName, e => e.ControlName, (d, accounts) => new {d, accounts})
                .Where(a => !a.accounts.Any())
                .Select(a => a.d.ControlName);

            foreach (string controlName in missedAccounts)
            {
                Console.WriteLine(controlName);
            }

            Console.WriteLine();
        }

这将输出：

收入控制信任控制税控

以下是沙箱的链接：http://rextester.com/EBLZ71941

使用linq可以提高效率吗？或者有人可以建议更快的算法而不使用linq？

Answer 1

由于您只对ControlName属性感兴趣，Except会更有效：

IEnumerable<string> missedAccounts = defaultAccounts.Select(a => a.ControlName)
    .Except(existingAccounts.Select(a => a.ControlName));

Answer 2

您是否了解Intersect()和Except()预定义函数？

Intersect() - 在两个列表/集合之间找到公共项目

Except() - 找到第一个集合中的项目以外的项目（按订单定义）

过滤一个集合中的项目，这些项目在另一个集合中不存在 - LINQ方式

2 个答案: