private static void RandomPointsComparer(IPointDComparer comparer)
{
RectD bounds = new RectD(-100, -100, 200, 200);
PointD[] points = GeoAlgorithms.RandomPoints(100, bounds, comparer, 2);
for (int i = 0; i < points.Length; i++)
{
PointD p = points[i];
Assert.IsTrue(bounds.Contains(p));
if (i > 0)
{
Assert.AreEqual(+1, comparer.Compare(p, points[i - 1]));
}
if (i < points.Length - 1)
{
Assert.AreEqual(-1, comparer.Compare(p, points[i + 1]));
}
for (int j = 0; j < points.Length; j++)
{
if (i == j)
{
continue;
}
double distance = p.Subtract(points[j]).LengthSquared;
Assert.GreaterOrEqual(distance, 4);
}
}
}
/// <summary>
/// Creates an <see cref="Array"/> of random <see cref="PointD"/> coordinates within the
/// specified area, ensuring a specified pairwise minimum distance.</summary>
/// <param name="count">
/// The number of <see cref="PointD"/> coordinates to create.</param>
/// <param name="bounds">
/// The coordinates of the area containing all <see cref="PointD"/> coordinates.</param>
/// <param name="comparer">
/// The <see cref="IPointDComparer"/> instance used to sort and search the collection of
/// <see cref="PointD"/> coordinates.</param>
/// <param name="distance">
/// The smallest Euclidean distance between any two <see cref="PointD"/> coordinates.
/// </param>
/// <returns>
/// An <see cref="Array"/> containing <paramref name="count"/> randomly created <see
/// cref="PointD"/> coordinates whose pairwise distance is equal to or greater than
/// <paramref name="distance"/>.</returns>
/// <exception cref="ArgumentNullException">
/// <paramref name="comparer"/> is a null reference.</exception>
/// <exception cref="ArgumentOutOfRangeException"><para>
/// <paramref name="count"/> is less than zero.
/// </para><para>-or-</para><para>
/// <paramref name="bounds"/> contains a <see cref="RectD.Width"/> or <see
/// cref="RectD.Height"/> that is equal to or less than zero.
/// </para><para>-or-</para><para>
/// <paramref name="distance"/> is equal to or less than zero.</para></exception>
/// <remarks><para>
/// The returned <see cref="Array"/> is sorted using the specified <paramref
/// name="comparer"/>, and never contains duplicate <see cref="PointD"/> coordinates.
/// </para><note type="caution">
/// <b>RandomPoints</b> may enter an endless loop if <paramref name="distance"/> is too
/// great relative to <paramref name="count"/> and <paramref name="bounds"/>.
/// </note></remarks>
public static PointD[] RandomPoints(int count,
RectD bounds, IPointDComparer comparer, double distance)
{
if (count < 0)
{
ThrowHelper.ThrowArgumentOutOfRangeException(
"count", count, Strings.ArgumentNegative);
}
if (bounds.Width <= 0 || bounds.Height <= 0)
{
ThrowHelper.ThrowArgumentOutOfRangeException(
"bounds", bounds, Strings.ArgumentCoordinatesInvalid);
}
if (comparer == null)
{
ThrowHelper.ThrowArgumentNullException("comparer");
}
if (distance <= 0)
{
ThrowHelper.ThrowArgumentOutOfRangeException(
"distance", distance, Strings.ArgumentNotPositive);
}
distance *= distance;
List <PointD> points = new List <PointD>(count);
for (int i = 0; i < count; i++)
{
createPoint:
PointD point = new PointD(
bounds.X + MersenneTwister.Default.NextDouble() * bounds.Width,
bounds.Y + MersenneTwister.Default.NextDouble() * bounds.Height);
if (points.Count > 0)
{
int index = comparer.FindNearest(points, point);
if (point.Subtract(points[index]).LengthSquared < distance)
{
goto createPoint;
}
}
points.Add(point);
points.Sort(comparer);
}
return(points.ToArray());
}
