我有大约250,000条记录标记为Boss,每个Boss有2到10名职员.我每天都需要了解员工的详细信息.大约有1,000,000名员工.我正在使用
Linq获取每日工作人员的唯一列表.考虑以下C#LINQ和模型
void Main()
{
List<Boss> BossList = new List<Boss>()
{
new Boss()
{
EmpID = 101,Name = "Harry",Department = "Development",Gender = "Male",Employees = new List<Person>()
{
new Person() {EmpID = 102,Name = "Peter",Gender = "Male"},new Person() {EmpID = 103,Name = "Emma Watson",Gender = "Female"},}
},new Boss()
{
EmpID = 104,Name = "Raj",Employees = new List<Person>()
{
new Person() {EmpID = 105,Name = "Kaliya",..... ~ 250,000 Records ......
};
List<Person> staffList = BossList
.SelectMany(x =>
new[] { new Person { Name = x.Name,Department = x.Department,Gender = x.Gender,EmpID = x.EmpID } }
.Concat(x.Employees))
.GroupBy(x => x.EmpID) //Group by employee ID
.Select(g => g.First()) //And select a single instance for each unique employee
.ToList();
}
public class Person
{
public int EmpID { get; set; }
public string Name { get; set; }
public string Department { get; set; }
public string Gender { get; set; }
}
public class Boss
{
public int EmpID { get; set; }
public string Name { get; set; }
public string Department { get; set; }
public string Gender { get; set; }
public List<Person> Employees { get; set; }
}
在上面的LINQ中我得到了不同员工或员工名单,该列表包含超过1,000条记录.从获得的列表中我需要搜索“Raj”
staffList.Where(m => m.Name.ToLowerInvariant().Contains("Raj".ToLowerInvariant()));
对于此操作,获得结果需要3到5分钟.
我怎么能让它更有效率.请帮助我……
解决方法
如果你改变Boss继承Person(公共类Boss：Person),你不仅不需要在Person和Boss中复制你的属性,你不必为每个Boss创建所有新的Person实例,因为Boss已经是一个人：
IEnumerable<Person> staff = BossList
.Concat(BossList
.SelectMany(x => x.Employees)
)
.DistinctBy(p => p.EmpId)
.ToList()
DistinctByis定义为
public static IEnumerable<TSource> DistinctBy<TSource,TKey>
(this IEnumerable<TSource> source,Func<TSource,TKey> keySelector)
{
var seenKeys = new HashSet<TKey>();
foreach (TSource element in source)
{
if (seenKeys.Add(keySelector(element)))
{
yield return element;
}
}
}
此外,在您的比较中,您将每个Name转换为小写并进行比较 – 这是您不需要的大量字符串创建.相反,尝试类似的东西
staffList.Where(m => m.Name.Equals("Raj",StringComparison.InvariantCultureIgnoreCase));
此外,请注意,您对Contains的使用也会与Rajamussen和mirajii等名称相匹配 – 可能不是您所期望的.
