CODEWITHSUNDEEP
c#linqlist
Myesil
Myesil

Reputation: 3

How to sort multiple list properties?

I have list list myList which has over 12 million elements. myClass has two properties ie. "gt" and "gm". I want to find maximum "gt" elements and choose that has min "gm". forexample: let myList such as:(first column is gt other is gm)

  4 1
  5 2
  7 1
  8 3
  4 3
  2 2
  8 7
  1 7
  8 2

I want to get the myClass element which has gt=8,gm=2. Where can I start?is sorting gt descending order an efficent way?

Upvotes: 0

Views: 100

Answers (2)

dcastro
dcastro

Reputation: 68640

myList.OrderByDescending(x => x.gt)                                  
      .ThenBy(x => x.gm)
      .First();

A more efficient, but less readbale way would be using Enumerable.Aggregate which iterates the collection once, and thus executes in O(n) time:

var seed = myList.First()
myList.Aggregate(seed, 
        (max, item) => {
            if(item.gt > max.gt)
                return item;
            if(item.gt == max.gt && item.gm < max.gm)
                return item;
            return max;
        });

Before going with the more efficient approach, measure both and make sure the readability-performance trade-off is worth it.

Upvotes: 2

Alexander Bell
Alexander Bell

Reputation: 7918

There is an Array.Max() method, which can be useful in your case, provided that you converted List to Array (using for example, List<T>.ToArray() Method as explained here: http://msdn.microsoft.com/en-us/library/x303t819%28v=vs.110%29.aspx). Regards,

Upvotes: 0

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