How can I reduce IEnumerable<IEnumerable<Foo>> to IEnumerable<Foo>?

Question

Sorry for the weird caption. What I'm trying to achieve is simple:

IEnumerable<IEnumerable<Foo>> listoflist;
IEnumerable<Foo> combined = listoflist.CombineStuff();

Example:

{{0, 1}, {2, 3}} => {0, 1, 2, 3}

I'm positive there is a Linq expression for this...

Sidenote: The lists may be large.

Answer 1

SelectMany()

OK

Answer 2

As leppie says, you want Enumerable.SelectMany. The simplest form would be:

 combined = listOfList.SelectMany(x => x);

In query expressions, SelectMany is called when you have more than one from clause, so an alternative would be:

 combined = from x in listOfList
            from y in x
            select y;