Add a Median Method to a List

Question

I would like to override the List object in C# in order to add a Median method like Sum or Average. I already found this function:

public static decimal GetMedian(int[] array)
{
    int[] tempArray = array;
    int count = tempArray.Length;

    Array.Sort(tempArray);

    decimal medianValue = 0;

    if (count % 2 == 0)
    {
        // count is even, need to get the middle two elements, add them together, then divide by 2
        int middleElement1 = tempArray[(count / 2) - 1];
        int middleElement2 = tempArray[(count / 2)];
        medianValue = (middleElement1 + middleElement2) / 2;
    }
    else
    {
        // count is odd, simply get the middle element.
        medianValue = tempArray[(count / 2)];
    }

    return medianValue;
}

Can you tell me how to do that?

Answer 1

Use an extension method, and make a copy of the inputted array/list.

public static decimal GetMedian(this IEnumerable<int> source)
{
    // Create a copy of the input, and sort the copy
    int[] temp = source.ToArray();    
    Array.Sort(temp);

    int count = temp.Length;
    if (count == 0)
    {
        throw new InvalidOperationException("Empty collection");
    }
    else if (count % 2 == 0)
    {
        // count is even, average two middle elements
        int a = temp[count / 2 - 1];
        int b = temp[count / 2];
        return (a + b) / 2m;
    }
    else
    {
        // count is odd, return the middle element
        return temp[count / 2];
    }
}