What is faster in finding element with property of maximum value

Question

Commonly, to find element with property of max value I do like this

var itemWithMaxPropValue = collection.OrderByDescending(x => x.Property).First();
         


        

Answer 1

Both solutions are not very efficient. First solution involves sorting whole collection. Second solution requires traversing collection two times. But you can find item with max property value in one go without sorting collection. There is MaxBy extension in MoreLINQ library. Or you can implement same functionality:

public static TSource MaxBy(this IEnumerable source,
    Func selector)
{
    // check args        

    using (var iterator = source.GetEnumerator())
    {
        if (!iterator.MoveNext())            
            throw new InvalidOperationException();

        var max = iterator.Current; 
        var maxValue = selector(max);
        var comparer = Comparer.Default;

        while (iterator.MoveNext())
        {
            var current = iterator.Current;
            var currentValue = selector(current);

            if (comparer.Compare(currentValue, maxValue) > 0)
            {
                max = current;
                maxValue = currentValue;
            }
        }

        return max;
    }
}

Usage is simple:

var itemWithMaxPropValue = collection.MaxBy(x => x.Property);