I want to count number of occurance of specific group in Generic List

Question

I have two class .

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

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" });

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

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

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)

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

Why are you using a string to store counts? Have you tried something? Did you encounter some problem? Or are you asking in general how to calculate groups? — Panagiotis Kanavos, Nov 10 '16 at 11:45
Since you already tagged this `LINQ`, you should google for `LINQ GROUP COUNT`. The very first result is a highly-upvoted duplicate — Panagiotis Kanavos, Nov 10 '16 at 11:48
Duplicate questions add noise that make it harder for the next person to find a good answer. That's why they are discouraged. — Panagiotis Kanavos, Nov 10 '16 at 11:59

Gilad Green · Accepted Answer · 2016-11-10T14:03:24.223

3

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()
}

In method syntax it will look like this:

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

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

edited Nov 10 '16 at 14:03

answered Nov 10 '16 at 11:44

Gilad Green

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Seems here `CountFirstName = grouping.Count()` need to add `ToString()` at the end, right? – Roman Marusyk Nov 10 '16 at 11:50
1

@MegaTron a better option would be to change the field to an integer, and leave formatting to the presentation layer, eg the MVC View – Panagiotis Kanavos Nov 10 '16 at 11:51
yes @PanagiotisKanavos, I agree but it was just a small remark to make these code working on OP source – Roman Marusyk Nov 10 '16 at 11:53
1

@MegaTron - you are correct and ill add a comment but it is better not to convert it to a string – Gilad Green Nov 10 '16 at 11:57
@MegaTron the OP should have googled before adding *another* question about grouping, making it harder for the next guy to find an answer. Using the wrong type for a field is an annoying bug - typically the next question is "Why doesn't my number appear the way I want it to?" – Panagiotis Kanavos Nov 10 '16 at 11:58
@RonakPatel - Did this help you understand how to do it? – Gilad Green Nov 10 '16 at 14:04
Yes.got it..thanks everyone . – Ronak Patel Nov 11 '16 at 08:47
I already did it . – Ronak Patel Nov 11 '16 at 09:41
@RonakPatel - strange.. it should have a green V just under the score of the answer.. – Gilad Green Nov 11 '16 at 09:42
@Green. Lets enjoy . – Ronak Patel Nov 11 '16 at 09:51
@RonakPatel - cool thanks :) – Gilad Green Nov 11 '16 at 09:52

I want to count number of occurance of specific group in Generic List

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