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. stackoverflow.com/questions/720609/… — Eldho
– Eldho, Commented May 20, 2018 at 8:50
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 — user4214969
– user4214969, Commented May 20, 2018 at 8:53

Sweeper · Accepted Answer · 2018-05-20 08:57:00Z

4

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, 2018 at 8:57

Sweeper

292k23 gold badges260 silver badges438 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

ooh so this gets all the "thingInAList" ...things of all the lists??

@Herpn'nFoDerp yes it's like a flatMap function.