switch the positions of two points in a list

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Permalink Reply by David Rutten on July 5, 2016 at 7:27am

copyLocations[index1] = copyLocations[index2];

copyLocations[index2] = copyLocations[index1];

that's the mistake. By the time the second line executes copyLocations[index1] is already equal to copyLocations[index2]. So all you're doing is copying the same value back from index1 to index2.

If you want to swap two values, you need to keep one tucked away in a safe place during the swap:

Point3d cache = list[index1];

list[index1] = list[index2];

list[index2] = cache;

Permalink Reply by David Rutten on July 14, 2016 at 5:38am

If it's arrays then yes, pretty much the way you wrote:

Random random = new Random(1);

Point3d[][] population = new Point3d[50][];

for (int i = 0; i < population.Length; i++)

{

  population[i] = new Point3d[10];

  for (int j = 0; j < population[i].Length; j++)

  {

    double x = random.NextDouble();

    double y = random.NextDouble();

    double z = random.NextDouble();

    population[i][j] = new Point3d(x, y, z);

  }

}