Sort a list of objects based on an integer of the object field c#

Question

I have a list of joints

List<Joint> joints = new();

The Joint class looks like this:

class Joint
{
    private Node node1, node2;
    private int weight;

    public Joint(Node node1, Node node2)
    {
        this.node1 = node1;
        this.node2 = node2;
        weight = GetWeight();
    }
        
    private int GetWeight()
    {
        return (int)Math.Sqrt
                ((int)Math.Pow(node1.GetX() - node2.GetX(), 2) + 
                (int)Math.Pow(node1.GetY() - node2.GetY(), 2));
    }
}

I would like to sort the joints list based on the weight value it contains. Preferably in only a few lines

All of your properties and methods are private. How do you want to sort based on them? — Jamiec, Mar 07 '23 at 18:37

Dmitry Bychenko · Accepted Answer · 2023-03-07T18:42:36.053

3

To sort List<i> in place, all you need is Sort method:

joints.Sort((a, b) => a.GetWeight().CompareTo(b.GetWeight()));

Note, that you may want to make GetWeight method being public. An alternative is to make Joint being comparable:

public class Joint: IComparable<Joint> {
  ...
  public int CompareTo(Joint other) {
    if (other == null)
      return 1;

    return GetWeight().CompareTo(other.GetWeight());
  }
}

if Joint is comparable, you can put just

joints.Sort();

edited Mar 07 '23 at 18:42

answered Mar 07 '23 at 18:34

Dmitry Bychenko

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`GetWeight` is private in the OP code – Jamiec Mar 07 '23 at 18:36
2

@Jamiec -- that is because it is never polite to ask an object their weight :) – Hogan Mar 07 '23 at 18:38
Women, yes. Joints are happy to disclose their weight. – Jamiec Mar 07 '23 at 18:38
@Jamiec -- not this Joint apparently. Maybe it is shy. – Hogan Mar 07 '23 at 18:39
Why use sort over, orderby? – johnny 5 Mar 07 '23 at 18:41
2

@johnny 5: `OrderBy` creates overhead, `joints = joints.OrderBy(item => item.GetWeight()).ToList();` makes a new list. `OrderBy` is OK if we want two list: unsorted original and sorted one. – Dmitry Bychenko Mar 07 '23 at 18:47

Sort a list of objects based on an integer of the object field c#

1 Answers1