我想计算通用列表中特定组的出现次数 [英] I want to count number of occurance of specific group in Generic List

问题描述

我有两个课.

public  class Employee
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

我有以上课程的数据，请在下面检查.

I have data for above class , please check below .

  List<Employee> lstEmployee = new List<Employee>();
  lstEmployee.Add(new Employee() { FirstName = "Ronak", LastName = "Patel" });
  lstEmployee.Add(new Employee() { FirstName = "Ronak", LastName = "Patel" });
  lstEmployee.Add(new Employee() { FirstName = "Sanjay", LastName = "Patel" });
  lstEmployee.Add(new Employee() { FirstName = "Ronak", LastName = "Patel" });
  lstEmployee.Add(new Employee() { FirstName = "Sanjay", LastName = "Patel" });
  lstEmployee.Add(new Employee() { FirstName = "Ronak", LastName = "Patel" });
  lstEmployee.Add(new Employee() { FirstName = "Mohan", LastName = "Patel" });

我要过滤通用列表上方并绑定到下面的结构类中.

I want filter above generic list and bound into below structure class .

class CountEmployeeName
{
    public string FirstName { get; set; }
    public int CountFirstName { get; set; }
}

我想根据上面的数据像下面的示例那样绑定CountEmployeeName类对象.

I want bind CountEmployeeName class object as per above data like below sample .

FirstName    CountFirstName 
Ronak              4         (Ronak is 4 time in above Employee class list)
Sanjay             2         (Sanjay is 4 time in above Employee class list)
Mohan              1         (Mohan is 4 time in above Employee class list)

我想根据Employee List的给定数据，将CountEmployeeName类的Generic List像上面的输出一样绑定.

I want to bind Generic List of CountEmployeeName class like above output as per given data for Employee List .

推荐答案

使用linq group by，然后在select项目中使用第二种类型:

Use linq group by and then in the select project to your second type:

from item in lstEmployee
group item by item.FirstName into grouping
select new CountEmployeeName
{
    FirstName = grouping.Key,
    CountFirstName = grouping.Count()
}

在方法语法中，它将如下所示:

In method syntax it will look like this:

lstEmployee.GroupBy(item => item.FirstName)
                   .Select(grouping => new CountEmployeeName { 
                       FirstName = grouping.Key, 
                       CountFirstName = grouping.Count() 
                   });

请注意，我建议将CountFirstName更改为int而不是string

Note that I'd recommend changing the CountFirstName to an int rather than string

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