How to “zip” or “rotate” a variable number of lists?

Question

If I have a list containing an arbitrary number of lists, like so:

var myList = new List>()
{
    new List() { \"a\",          


        

Answer 1

How about using SelectMany and GroupBy with some indexes?

// 1. Project inner lists to a single list (SelectMany)
// 2. Use "GroupBy" to aggregate the item's based on order in the lists
// 3. Strip away any ordering key in the final answer
var query = myList.SelectMany(
    xl => xl.Select((vv,ii) => new { Idx = ii, Value = vv }))
       .GroupBy(xx => xx.Idx)
       .OrderBy(gg => gg.Key)
       .Select(gg => gg.Select(xx => xx.Value));

From LinqPad: