Intersect two collections which contain different types

Question

Suppose I have one collection, call it ids it is of type IEnumerable<string>, I have a second collection call it objects it's of type MyObject[]. MyObject has a string property called id. I would like a LINQ statement that returns all off the objects in the objects collection who's id matches any value in the ids collection. ids will be a strict subset of objects.Select(x => x.id). Meaning, for every string in ids I know there will be exactly one corresponding MyObject in objects. Can someone post a pure LINQ solution? I've tried a couple things with no luck. I can come up with an iterative solution easily enough so unless it's impossible to do with only LINQ please don't post any.

Answer 1

"Just" LINQ:

var r = obj.Where(o => ids.Any(id => id == o.id));

But better, for larger n, with a set:

var hs = new HashSet(ids);
var r = obj.Where(o => hs.Contains(o.id));