Getting odd/even part of a sequence with LINQ

Question

Say I have a list of all Projects, and that I group them by Category like this:

var projectsByCat = from p in Projects
                     


        

Answer 1

Note that calling .ToList() twice for the same query is going query the database twice.

It would be much better to cache the result in an intermediate list, then apply your predicate filtering:

var projectsByCat =
    (from p in Projects
    group p by p.Category into g
    orderby g.Count() descending
    select new { Category = g.Key, Projects = g }).ToList();

var oddCategories = projectsByCat.Where((cat, index) => index % 2 != 0);
var evenCategories = projectsByCat.Where((cat, index) => index % 2 == 0);