C# Collection - Order by an element (Rotate)

Question

I have an IEnumerable collection. Lets say it contains 5 points (in reality it is more like 2000)

I want to order this collection so that a spe

Answer 1

Version without enumerating list two times, but higher memory consumption because of the T[]:

public static IEnumerable Rotate(IEnumerable source, int count)
{
    int i = 0;

    T[] temp = new T[count];

    foreach (var item in source)
    {
        if (i < count)
        {
            temp[i] = item;
        }
        else
        {
            yield return item;
        }

        i++;
    }

    foreach (var item in temp)
    {
        yield return item;
    }
}

[Test]
public void TestRotate()
{
    var list = new[] { 1, 2, 3, 4, 5 };

    var rotated = Rotate(list, 3);

    Assert.That(rotated, Is.EqualTo(new[] { 4, 5, 1, 2, 3 }));
}

Note: Add argument checks.