/// <summary>
/// Computes the circular quartiles of the given circular angles.
/// </summary>
///
/// <param name="angles">A double array containing the angles in radians.</param>
/// <param name="q1">The first quartile, as an out parameter.</param>
/// <param name="q3">The third quartile, as an out parameter.</param>
/// <param name="median">The angular median, if already known.</param>
/// <param name="wrap">
/// Whether range values should be wrapped to be contained in the circle. If
/// set to false, range values could be returned outside the [+pi;-pi] range.
/// </param>
///
/// <returns>The median of the given angles.</returns>
///
public static double Quartiles(double[] angles, out double q1, out double q3, double median, bool wrap = true)
{
double[] x = new double[angles.Length];
for (int i = 0; i < angles.Length; i++)
{
x[i] = Accord.Math.Tools.Mod(angles[i] - median, 2 * Math.PI);
}
for (int i = 0; i < x.Length; i++)
{
x[i] = (x[i] < -Math.PI) ? (x[i] + (2 * Math.PI)) : (x[i]);
x[i] = (x[i] > +Math.PI) ? (x[i] - (2 * Math.PI)) : (x[i]);
}
Tools.Quartiles(x, out q1, out q3, alreadySorted: false);
q1 = q1 + median;
q3 = q3 + median;
if (wrap)
{
q1 = Accord.Math.Tools.Mod(q1, 2 * Math.PI);
q3 = Accord.Math.Tools.Mod(q3, 2 * Math.PI);
}
return(median);
}
public void QuartileTest3()
{
double[] values = new double[] { 102, 104, 105, 107, 108, 109, 110, 112, 115, 116, 118 };
double q1, q3, actual;
actual = Tools.Quartiles(values, out q1, out q3, false);
Assert.AreEqual(105, q1);
Assert.AreEqual(109, actual);
Assert.AreEqual(115, q3);
}
public void QuartileTest2()
{
double[] values = new double[] { 1, 3, 3, 4, 5, 6, 6, 7, 8, 8 };
double q1, q3, actual;
actual = Tools.Quartiles(values, out q1, out q3, false);
Assert.AreEqual(3, q1);
Assert.AreEqual(5.5, actual);
Assert.AreEqual(7, q3);
}
public void QuartileTest1()
{
double[] values = new double[] { 3, 4, 8 };
double q1, q3, actual;
actual = Tools.Quartiles(values, out q1, out q3, false);
Assert.AreEqual(3, q1);
Assert.AreEqual(4, actual);
Assert.AreEqual(8, q3);
}
public void QuartileTest4()
{
// This is equivalent to R's type 6. This is the
// same algorithm used by Minitab and SPSS. It is
// not the same used by R and S.
double[] values =
{
-0.309882133, -0.640157313179586, 0.00470721699999999,
-0.709738241179586, 0.328021416, -1.95662033217959,
0.618215405, 0.113038781, 0.311043694,-0.0662271140000001,
-0.314138172179586, 0, -0.220574326, 0.078498723, 0.287448082
};
double q1, q3, actual;
actual = Tools.Quartiles(values, out q1, out q3, false);
Assert.AreEqual(-0.31413817217958601, q1);
Assert.AreEqual(0, actual);
Assert.AreEqual(0.28744808199999999, q3);
}
