Linq "reporting" question with list properties - linq

Question

I have an entity object that contains a list property. I'd like to expand the list values to the right. Being new to LINQ, I'm not sure how to do this. I could strongly type an object, but then I'd have to know the count/values at compile time and I'd like to make it more dynamic.
The output that I'm wanting is something like:
Name Demo1 Demo2 Demo3
Person Name1 TX TX
Person Name2 TX OK
Person Name3 TX TX OK
Main Class
public Main()
{
List<Event> events = new List<Event>();
events.Add(new Event()
{
EventDate = DateTime.Now,
EventLocation = new Location() { State = "TX" },
EventName = "Demo1"
});
events.Add(new Event()
{
EventDate = DateTime.Now,
EventLocation = events[0].EventLocation,
EventName = "Demo2"
});
events.Add(new Event()
{
EventDate = DateTime.Now,
EventLocation = new Location() { State = "OK" },
EventName = "Demo3"
});
List<Person> people = new List<Person>();
Person person1 = new Person();
person1.Name = "Person Name1";
person1.Events.Add(events[0]);
person1.Events.Add(events[1]);
Person person2 = new Person();
person2.Name = "Person Name2";
person2.Events.Add(events[0]);
person2.Events.Add(events[2]);
Person person3 = new Person();
person3.Name = "Person Name3";
person3.Events.Add(events[0]);
person3.Events.Add(events[1]);
person3.Events.Add(events[2]);
people.Add(person1);
people.Add(person2);
people.Add(person3);
}

Answer 1

It depends on whether you want to run the query in memory or in databse. In any case, you'll need to return a list with the "dynamic" part of the results, because you cannot dynamically generate members of anonymous types (and working with them would be difficult).
In memory (as in your example), you can write the following query:
// Find names of all events (for all people)
var allNames =
(from p in people
from e in p.Events
select e.EventName).Distinct();
// Find events for every person
var res =
from p in people
let known = p.Events.ToDictionary(e => e.EventName)
select new {
p.Name,
Events = allNames.Select(n =>
known.ContainsKey(n)?known[n].EventLocation:"N/A")
};
The first query gets names of all events (we use it later to find a value for all event for every person). The second query iterates over all people. It first creates dictionary with events (for fast lookup in memory) and then iterates over all event names and tries to find them in the dictionary (returning "N/A" if it is not found).