How to use LINQ to get a single IENumerable from a property of an IEnumerable?

Question

Consider the following array:

class B { }

class A 
{
    IEnumerable<B> C { get; }
}

IEnumerable<A> array;

I need to end up with one IEnumerable<B>. I'm ending up with IEnumerable<IEnumerable<B>>:

var q = array.Select(a => a.C);

How can I unwind the array?

You didn't show us the code you're using to get `IEnumerable>`. It's not at all clear what you're asking. — Robert Harvey, Dec 11 '12 at 15:41
What do you mean by unwind? Do you mean transforming a two dimensional array into a single dimensional array? — Ryan Gates, Dec 11 '12 at 15:42

score 7 · Accepted Answer · answered Dec 11 '12 at 15:41

7

You just need to use SelectMany:

IEnumerable<B> allBs = array.SelectMany(a => a.C);

answered Dec 11 '12 at 15:41

Rawling

Crystal ball analysis at its finest. – Robert Harvey Dec 11 '12 at 15:43
@RobertHarvey Not really, I was just privy to the [original question](http://stackoverflow.com/questions/13822750/how-to-use-linq-on-a-multidimensional-array-to-unwind-the-array) where OP generalized this in a way that didn't really generalize, then edited his question to degeneralize it, then had his edit rolled back because people had answered the original. – Rawling Dec 11 '12 at 15:45

score 3 · Answer 2 · answered Dec 11 '12 at 15:41

3

Use SelectMany:

var q = array.SelectMany(a => a.C);

This will give you an IEnumerable<B> containing the flattened contents of the C property of each item in array.

answered Dec 11 '12 at 15:41

Jon B

2 Answers2