LINQ Max() with Nulls

Question

I have a list that contains a bunch of Points (with an X and Y component).

I want to get the Max X for all points in the list, like this:

double max          


        

Answer 1

Well, you could just filter them out:

pointList.Where(p => p != null).Max(p => p.X)

On the other hand, if you want nulls to be treated as though they were points having X-coordinate 0 (or similar), you could do:

pointList.Max(p => p == null ? 0 : p.X)

Do note that both techniques will throw if the sequence is empty. One workaround for this (if desirable) would be:

pointList.DefaultIfEmpty().Max(p => p == null ? 0 : p.X)

Answer 2

If you want to provide a default value for X of a null point:

pointList.Max(p => p == null ? 0 : p.X)

Or to provide a default for an empty list:

int max = points.Where(p => p != null)
                .Select(p => p.X)
                .DefaultIfEmpty()
                .Max();