private void CalculatePressureTrend()
{
var pressureData = _database
.GetReadingValueHistory(WeatherValueType.Pressure, Timestamp.AddHours(-3), Timestamp).Result.ToList();
var xData = pressureData.Select(p => (double)p.Timestamp.ToUnixTimeSeconds()).ToArray();
var yData = pressureData.Select(p => (double)p.Value / 100.0).ToArray();
var lineFunction = Fit.LineFunc(xData, yData);
PressureDifferenceThreeHour = (decimal)(lineFunction(xData.Last()) - lineFunction(xData[0]));
}
public void FitsToExactLineWhenPointsAreOnLine()
{
var x = new[] { 30.0, 40.0, 50.0, 12.0, -3.4, 100.5 };
var y = x.Select(z => 4.0 - 1.5 * z).ToArray();
var resp = Fit.Line(x, y);
Assert.AreEqual(4.0, resp.Item1, 1e-12);
Assert.AreEqual(-1.5, resp.Item2, 1e-12);
var resf = Fit.LineFunc(x, y);
foreach (var z in Enumerable.Range(-3, 10))
{
Assert.AreEqual(4.0 - 1.5 * z, resf(z), 1e-12);
}
}
public void FitsToBestLine()
{
// Mathematica: Fit[{{1,4.986},{2,2.347},{3,2.061},{4,-2.995},{5,-2.352},{6,-5.782}}, {1, x}, x]
// -> 7.01013 - 2.08551*x
var x = Enumerable.Range(1, 6).Select(Convert.ToDouble).ToArray();
var y = new[] { 4.986, 2.347, 2.061, -2.995, -2.352, -5.782 };
var resp = Fit.Line(x, y);
Assert.AreEqual(7.01013, resp.Item1, 1e-4);
Assert.AreEqual(-2.08551, resp.Item2, 1e-4);
var resf = Fit.LineFunc(x, y);
foreach (var z in Enumerable.Range(-3, 10))
{
Assert.AreEqual(7.01013 - 2.08551 * z, resf(z), 1e-4);
}
}
public void FitsToLineSameAsExcelTrendLine()
{
// X Y
// 1 0.2
// 2 0.3
// 4 1.3
// 6 4.2
// -> y = -1.078 + 0.7932*x
var x = new[] { 1.0, 2.0, 4.0, 6.0 };
var y = new[] { 0.2, 0.3, 1.3, 4.2 };
var resp = Fit.Line(x, y);
Assert.AreEqual(-1.078, resp.Item1, 1e-3);
Assert.AreEqual(0.7932, resp.Item2, 1e-3);
var resf = Fit.LineFunc(x, y);
foreach (var z in Enumerable.Range(-3, 10))
{
Assert.AreEqual(-1.078 + 0.7932 * z, resf(z), 1e-2);
}
}
public virtual Func <double, double> LinearFittingFunc(double[] x, double[] y)
{
return(Fit.LineFunc(x, y));
}
