Euclidean distance between the coordinates in the array

Question

I calculate euclidean distance in c#.

Point[] points = new Point[100];

I have the coordinates of the points I created in this array.I want to calculate the distance between all points.

for (int i = 1; i < k+1; i++)
 {

     X1 = points[i].X;
     X2 = points[i + 1].X;
     Y1 = points[i].Y;
     Y2 = points[i + 1].Y;
     result = Math.Sqrt((X1 - X2) * (X1 - X2) + (Y1 - Y2) * (Y1 - Y2));

}

With this code I have calculated the distance between points (eg: distance between points a and b, distance between points c and d, etc.) but I couldn't calculate the distance between points a and c or the points b and b I want to calculate the distance between all points in this array. How do I do that?

Your code needs to do two things: 1) Pick two points to calculate the distance between; 2) Calculate the distance between those points. It sounds like the problem is really in part 1, not part 2. One way of making this clearer is to separate out the distance calculation into a method, e.g. `double CalculateDistance(Point p1, Point p2)`. Then you can focus everything on working out which points to compare. (Hint: you'll probably want two loops. I'd also recommend using a 0-based counter, as that's how arrays etc work naturally in C#.) — Jon Skeet, Dec 09 '18 at 09:13
[How to visually connect 2 circles?](https://stackoverflow.com/a/52921415/7444103) — Jimi, Dec 09 '18 at 09:26

score 1 · Accepted Answer · answered Dec 09 '18 at 10:47

1

You have to use 2 loops. The first loop assign values to X1 and the second loop assign values to X2.

This allows to calculate the Euclidean Distance between two points that aren't contiguous in the array.

answered Dec 09 '18 at 10:47

EloyBG

46
2

score 0 · Answer 2 · answered Dec 09 '18 at 09:49

0

You have to use 2 for loops to achieve that.

Also you would want to persist the euclidean distances between these points somewhere.

answered Dec 09 '18 at 09:49

amanmehara

134
1
8

score 0 · Answer 3 · answered Dec 09 '18 at 11:12

You probably want to go through the array twice.

Point[] points = new Point[100];
for(int i = 0; i < points.Length; i++)
    for (int j = points.Length - 1; j >= i; j--)
    {
        float distance = 0;
        if(i != j)
            distance = CalculateDistance(points[i], points[j]);
        // Do more stuff here
    }

Obviously, you could simply run two for loops of equal lengths, but this will give you the same result twice. When i and j have the same value flipped (i = 10, j = 15 and later i = 15 and j = 10), you do the same calculation to get the same result. To prevent that I have my second loop only run about half the values to not redo calculations.

The CalculateDistance method does exactly the same as the code you have written before, in my case the following:

private static float CalculateDistance(Point point1, Point point2)
{
    float X1 = point1.X;
    float X2 = point1.Y;
    float Y1 = point2.X;
    float Y2 = point2.Y;
    return (float)Math.Sqrt((X1 - X2) * (X1 - X2) + (Y1 - Y2) * (Y1 - Y2));
}

This way I can reuse and reorder my calculations at any time, because I only have to move a single line. Note that you can always just use the floats as parameters instead of locals, but I felt like this way would make it more readable here in this example.

I also skipped the calculations when the distance was equal, because the same values were compared.

score 0 · Answer 4 · answered Dec 09 '18 at 11:19

public void Euclidea()
        {
            double result;
            int X1,X2,Y1,Y2;

            for (int i = 1; i < k+1; i++)
            {
                X1 = points[i].X;
                Y1 = points[i].Y;
                for (int j = 0; j < k; j++)
                {
                    X2 = points[j + 1].X;
                    Y2 = points[j + 1].Y;
                    result = Math.Sqrt((X1 - X2) * (X1 - X2) + (Y1 - Y2) * (Y1 - Y2));
                }
            }
        }

I solved the problem by typing this code k=points.length()

Euclidean distance between the coordinates in the array

4 Answers4