CODEWITHSUNDEEP
c#arraysperformancesortingquicksort
Alessio Il Pierce Giannelli
Alessio Il Pierce Giannelli

Reputation: 129

Fastest way to sort an Array c#

Hi this is my problem I have an array of points P(x,y) and I need to sort these points from the furthest to the closest, respect to the barycenter of a Polygon, this what I have done (I know this is a bad solution ) how can I do a better and aboveall faster solution? 

List<C2DPoint> OrderedGripperPoints = new List<C2DPoint> { };

while(myGripperPoints.Count!=0) 
{
    double dist=-1;
    int index=-1;
    for(int k=0;k<myGripperPoints.Count;k++)
    {
        if(myGripperPoints[k].Distance(WorkScrap.GetCentroid())>=dist)
        {
            index = k;
            dist = myGripperPoints[k].Distance(WorkScrap.GetCentroid());
        }
    }

    OrderedGripperPoints.Add(myGripperPoints[index]);
    myGripperPoints.RemoveAt(index);
}

Thanks for your answers...

Upvotes: 0

Views: 2508

Answers (2)

Mrinal Kamboj
Mrinal Kamboj

Reputation: 11478

Consider the following code:

Point Class (assumed class definition)

class Point
{
    public int X { get; set;}

    public int Y { get; set;}   
}

Point EqualityComparer

class PointEqualityComparer : IEqualityComparer<Point>
{
    public bool Equals(Point p1, Point p2) { return p1.X == p2.X && p1.Y == p2.Y; }

    public int GetHashCode(Point p) { return p.X.GetHashCode() *31 + p.Y.GetHashCode()*23; }
}

Create a Dictionary with Point as Key and Distance as value (assuming integer):

Dictionary<Point,int> pointDictionary = 
new Dictionary<Point, int>(new PointEqualityComparer());

Add Points as follows:

Point p = new Point {X = <value>, Y = <value>};
pointDictionary.Add(p,p.Distance(WorkScrap.GetCentroid()));

Order by Distance as follows:

pointDictionary.OrderByDescending(x => x.Value).ToList();
  1. Ordering is done by Distance in Descending order as expected
  2. Result would be List<KeyValuePair<Point,int>>, where elements are in Descending order

Upvotes: 1

selami
selami

Reputation: 2498

Use Linq to order points.

using System.Linq;

var sortedList = myGripperPoints.OrderBy(p => p.Distance(WorkScrap.GetCentroid())).ToList();

Upvotes: 4

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