LINQ OrderBy custom order

Question

Say I have the following character array:

char[] c = new char[] { 'G', 'R', 'D', 'D', 'G', 'R', 'R', 'C', 'D', 'G', 'R', 'R', 'C', 'G', 'R', 'D', 'D', 'G', 'R', 'R', 'C', 'D', 'G', 'R', 'R', 'C' };


c.OrderBy(y => y).ForEach(x => Console.WriteLine(x));
//CCCCDDDDDDGGGGGGRRRRRRRRRR

How do I use LINQ to produce the following order?

//DDDDDDGGGGGGRRRRRRRRRRCCCC

Answer 1

Maybe you want to do something like this:

char [] customOrder = { 'D', 'G', 'R', 'C'};
char [] c = new char[] { 'G', 'R', 'D', 'D', 'G', 'R',
                         'R', 'C', 'D', 'G', 'R', 'R',
                         'C', 'G', 'R', 'D', 'D', 'G',
                         'R', 'R', 'C', 'D', 'G', 'R', 'R', 'C' };

foreach (char item in c.OrderBy(ch => Array.IndexOf(customOrder, ch))) {
    Console.Write(item);
}

Answer 2

You could use another collection which defines the order:

char[] order = {'D','G','R','C'};
var customOrder = c.OrderBy(chr =>
{
    int index = Array.IndexOf(order, chr);
    if (index == -1) return int.MaxValue;
    return index;
});