Linq Unique Values - linq

Question

i have a list of generic class which consists of 2 string property and 1 List as a property
code snipnets is as follows:
public Class abc
{
public int ID { get; set; }
public String Name { get; set; }
List<String> myList;
public List<String> Subjects
{
get
{
if (myList == null)
{
myList = new List<string>();
}
return myList;
}
}
public abc()
{
}
public abc(int id, String name, params string[] subjects)
{
Subjects.AddRange(subjects.AsEnumerable<String>());
ID = id;
Name = name;
}
}
List<abc> myList = new List<abc>();
myList.Add(new abc(1, "p1", "Maths", "Science"));
myList.Add(new abc(2, "p2", "Maths", "Art"));
myList.Add(new abc(3, "p3", "Art", "Science"));
myList.Add(new abc(4, "p4", "Geometry", "Maths"));
I need the output as
Subject Count Person
Maths 3 p1,p2,p4
Science 2 p1,p3
Art 2 p2,p3
Geometry 1 p4

Answer 1

Looks like you want something like:
var query = from item in myList
from subject in item.Subjects
group item.Name by subject into g
select new { Subject = g.Key,
Count = g.Count(),
Person = string.Join(",", g) };
(Change g into g.ToArray() in the string.Join call if you're using .NET 3.5.)

Answer 2

var result =myList.SelectMany(p => p.Subjects
.Select(q => new{Person = p.Name, Subject = q, ID = p.ID}))
.GroupBy(p => p.Subject)
.Select(p => new {Name = p.Key, Count = p.Count(), Persons = p
.Aggregate("", (a, b) => a + b.Person
+ ",").TrimEnd(',')}).OrderBy( p => p.Count);
Iterate over this collection, and print result as needed - properties of a result are Name, Count, Persons