Concatenate lists with LINQ

Question

Is it possible to concatenate a List<List<T>> into a List<T> with a single operation in a way which isn't horrible slow, i.e:

List<List<int>> listOfLists = new List<List<int>>();
List<int> concatenatedList = listOfLists.Something...

?

Actually, it IS called concatenation, http://msdn.microsoft.com/en-us/library/ee353462.aspx. — John Reynolds, Aug 17 '11 at 14:54

Andrey · Accepted Answer · 2011-01-19T11:22:56.147

27

listOfLists.SelectMany( l => l );

full line:

List<int> concatenatedList = listOfLists.SelectMany( l => l ).ToList();

edited Jan 19 '11 at 11:22

answered Jan 19 '11 at 11:15

Andrey

score 0 · Answer 2 · answered Jan 19 '11 at 11:20

0

Something like this:

listOfLists.Aggregate(new int[0], (res, list) => res.Concat(list));

answered Jan 19 '11 at 11:20

Victor Haydin

2 Answers2