C# Linq merge multiple lists?

Question

var results = from thing in AnArrayOfThings
              let list = Function(thing)
              ???
              select OneLongResultsList;

How can I merge all the "list" collections into one long list? I'm new to linq and I can't use lambda expressions.

Basically, what I want to do, is this:

List<Result> results = new ...;
foreach (Thing t in ListOfThings)
{
    List<Result> list = Function( t );
    results.MergeOrAdd( list );
}

Is two list are same type? Try some tutorials. Concat , Union are some of methods. https://stackoverflow.com/questions/720609/create-a-list-from-two-object-lists-with-linq — Eldho, May 20 '18 at 08:50
[Merge two (or more) lists into one, in C# .NET](https://stackoverflow.com/a/4488061/1417185) — Paritosh, May 20 '18 at 08:52
Yes, they are the same type. Concat works with two lists, which I don't know how to adapt to multiple, like in a foreach loop — , May 20 '18 at 08:53

score 3 · Accepted Answer · answered May 20 '18 at 08:57

3

Maybe you just need SelectMany?

var results = AnArrayOfThings.SelectMany(x => Function(x));

Or in query syntax:

var results = from thing in AnArrayOfThings
              from thingInAList in Function(thing)
              select thingInAList;

answered May 20 '18 at 08:57

Sweeper

ooh so this gets all the "thingInAList" ...things of all the lists?? – May 20 '18 at 09:00
@Herpn'nFoDerp yes it's like a flatMap function. – Sweeper May 20 '18 at 09:01

1 Answers1